Extract nu_source into a crate

This commit extracts Tag, Span, Text, as well as source-related debug
facilities into a new crate called nu_source.

This change is much bigger than one might have expected because the
previous code relied heavily on implementing inherent methods on
`Tagged<T>` and `Spanned<T>`, which is no longer possible.

As a result, this change creates more concrete types instead of using
`Tagged<T>`. One notable example: Tagged<Value> became Value, and Value
became UntaggedValue.

This change clarifies the intent of the code in many places, but it does
make it a big change.

Cargo.lock

@@ -1704,6 +1704,7 @@ dependencies = [
  "nom 5.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "nom-tracable 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "nom_locate 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nu-source 0.1.0",
  "num-bigint 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "onig_sys 69.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1746,6 +1747,20 @@ dependencies = [
  "which 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "nu-source"
+version = "0.1.0"
+dependencies = [
+ "derive-new 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "getset 0.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "language-reporting 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nom-tracable 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nom_locate 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pretty 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.102 (registry+https://github.com/rust-lang/crates.io-index)",
+ "termcolor 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.2.3"

Cargo.toml

@@ -11,9 +11,15 @@ repository = "https://github.com/nushell/nushell"
 homepage = "https://www.nushell.sh"
 documentation = "https://book.nushell.sh"
 
+[workspace]
+
+members = ["crates/nu-source"]
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+nu-source = { path = "./crates/nu-source" }
+
 rustyline = "5.0.4"
 chrono = { version = "0.4.9", features = ["serde"] }
 derive-new = "0.5.8"
@@ -80,7 +86,7 @@ strip-ansi-escapes = "0.1.0"
 calamine = "0.16"
 umask = "0.1"
 futures-util = "0.3.0"
-pretty = { version = "0.5.2" }
+pretty = "0.5.2"
 termcolor = "1.0.5"
 console = "0.9.1"
 
@@ -96,7 +102,6 @@ ptree = {version = "0.2" }
 image = { version = "0.22.2", default_features = false, features = ["png_codec", "jpeg"], optional = true }
 starship = { version = "0.26.4", optional = true}
 
-
 [features]
 default = ["textview", "sys", "ps"]
 raw-key = ["rawkey", "neso"]

TODO.md

@@ -0,0 +1,50 @@
+This pattern is extremely repetitive and can be abstracted:
+
+```rs
+    let args = args.evaluate_once(registry)?;
+    let tag = args.name_tag();
+    let input = args.input;
+
+    let stream = async_stream! {
+        let values: Vec<Value> = input.values.collect().await;
+
+        let mut concat_string = String::new();
+        let mut latest_tag: Option<Tag> = None;
+
+        for value in values {
+            latest_tag = Some(value_tag.clone());
+            let value_span = value.tag.span;
+
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
+                    concat_string.push_str(&s);
+                    concat_string.push_str("\n");
+                }
+                _ => yield Err(ShellError::labeled_error_with_secondary(
+                    "Expected a string from pipeline",
+                    "requires string input",
+                    name_span,
+                    "value originates from here",
+                    value_span,
+                )),
+
+            }
+        }
+
+```
+
+Do we need Display impls?
+
+Mandatory and Optional in parse_command
+
+trace_remaining?
+
+select_fields and select_fields take unnecessary Tag
+
+Value#value should be Value#untagged
+
+Unify dictionary building, probably around a macro
+
+sys plugin in own crate
+
+textview in own crate

crates/nu-source/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "nu-source"
+version = "0.1.0"
+authors = ["Yehuda Katz <wycats@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+serde = { version = "1.0.102", features = ["derive"] }
+derive-new = "0.5.8"
+getset = "0.0.9"
+nom_locate = "1.0.0"
+nom-tracable = "0.4.1"
+language-reporting = "0.4.0"
+termcolor = "1.0.5"
+pretty = "0.5.2"

crates/nu-source/src/lib.rs

@@ -0,0 +1,15 @@
+mod meta;
+mod pretty;
+mod term_colored;
+mod text;
+mod tracable;
+
+pub use self::meta::{
+    span_for_spanned_list, tag_for_tagged_list, AnchorLocation, HasFallibleSpan, HasSpan, HasTag,
+    Span, Spanned, SpannedItem, Tag, Tagged, TaggedItem,
+};
+pub use self::pretty::{
+    b, DebugDoc, DebugDocBuilder, PrettyDebug, PrettyDebugWithSource, ShellAnnotation,
+};
+pub use self::text::Text;
+pub use self::tracable::{nom_input, NomSpan, TracableContext};

crates/nu-source/src/meta.rs

@@ -1,13 +1,24 @@
-use crate::context::AnchorLocation;
-use crate::parser::parse::parser::TracableContext;
-use crate::prelude::*;
+use crate::pretty::{b, DebugDocBuilder, PrettyDebugWithSource};
+use crate::text::Text;
+use crate::tracable::TracableContext;
+
 use derive_new::new;
 use getset::Getters;
 use serde::Deserialize;
 use serde::Serialize;
-use std::fmt;
 use std::path::{Path, PathBuf};
 
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum AnchorLocation {
+    Url(String),
+    File(String),
+    Source(Text),
+}
+
+pub trait HasTag {
+    fn tag(&self) -> Tag;
+}
+
 #[derive(new, Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize, Hash)]
 pub struct Spanned<T> {
     pub span: Span,
@@ -62,6 +73,7 @@ impl<T> std::ops::Deref for Spanned<T> {
         &self.item
     }
 }
+
 #[derive(new, Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize, Hash)]
 pub struct Tagged<T> {
     pub tag: Tag,
@@ -79,6 +91,12 @@ impl Tagged<String> {
     }
 }
 
+impl<T> Tagged<Vec<T>> {
+    pub fn items(&self) -> impl Iterator<Item = &T> {
+        self.item.iter()
+    }
+}
+
 impl<T> HasTag for Tagged<T> {
     fn tag(&self) -> Tag {
         self.tag.clone()
@@ -184,14 +202,8 @@ impl From<&Tag> for Tag {
     }
 }
 
-impl From<nom_locate::LocatedSpanEx<&str, TracableContext>> for Span {
-    fn from(input: nom_locate::LocatedSpanEx<&str, TracableContext>) -> Span {
-        Span::new(input.offset, input.offset + input.fragment.len())
-    }
-}
-
-impl From<nom_locate::LocatedSpanEx<&str, u64>> for Span {
-    fn from(input: nom_locate::LocatedSpanEx<&str, u64>) -> Span {
+impl<T> From<nom_locate::LocatedSpanEx<&str, T>> for Span {
+    fn from(input: nom_locate::LocatedSpanEx<&str, T>) -> Span {
         Span::new(input.offset, input.offset + input.fragment.len())
     }
 }
@@ -330,6 +342,10 @@ impl Tag {
         }
     }
 
+    pub fn anchor(&self) -> Option<AnchorLocation> {
+        self.anchor.clone()
+    }
+
     pub fn until(&self, other: impl Into<Tag>) -> Tag {
         let other = other.into();
         debug_assert!(
@@ -376,6 +392,14 @@ impl Tag {
     pub fn tagged_string<'a>(&self, source: &'a str) -> Tagged<String> {
         self.span.slice(source).to_string().tagged(self)
     }
+
+    pub fn anchor_name(&self) -> Option<String> {
+        match self.anchor {
+            Some(AnchorLocation::File(ref file)) => Some(file.clone()),
+            Some(AnchorLocation::Url(ref url)) => Some(url.clone()),
+            _ => None,
+        }
+    }
 }
 
 #[allow(unused)]
@@ -418,6 +442,12 @@ pub struct Span {
     end: usize,
 }
 
+impl From<&Span> for Span {
+    fn from(span: &Span) -> Span {
+        *span
+    }
+}
+
 impl From<Option<Span>> for Span {
     fn from(input: Option<Span>) -> Span {
         match input {
@@ -514,11 +544,11 @@ impl language_reporting::ReportingSpan for Span {
     }
 }
 
-pub trait HasSpan: ToDebug {
+pub trait HasSpan: PrettyDebugWithSource {
     fn span(&self) -> Span;
 }
 
-pub trait HasFallibleSpan: ToDebug {
+pub trait HasFallibleSpan: PrettyDebugWithSource {
     fn maybe_span(&self) -> Option<Span>;
 }
 
@@ -530,31 +560,34 @@ impl<T: HasSpan> HasFallibleSpan for T {
 
 impl<T> HasSpan for Spanned<T>
 where
-    Spanned<T>: ToDebug,
+    Spanned<T>: PrettyDebugWithSource,
 {
     fn span(&self) -> Span {
         self.span
     }
 }
 
+impl PrettyDebugWithSource for Option<Span> {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
+        match self {
+            None => b::description("no span"),
+            Some(span) => span.pretty_debug(source),
+        }
+    }
+}
+
 impl HasFallibleSpan for Option<Span> {
     fn maybe_span(&self) -> Option<Span> {
         *self
     }
 }
 
-impl FormatDebug for Option<Span> {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        match self {
-            Option::None => write!(f, "no span"),
-            Option::Some(span) => FormatDebug::fmt_debug(span, f, source),
-        }
-    }
-}
-
-impl FormatDebug for Span {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        write!(f, "{:?}", self.slice(source))
+impl PrettyDebugWithSource for Span {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
+        b::typed(
+            "spanned",
+            b::keyword("for") + b::space() + b::description(format!("{:?}", source)),
+        )
     }
 }
 
@@ -564,21 +597,21 @@ impl HasSpan for Span {
     }
 }
 
-impl<T> FormatDebug for Option<Spanned<T>>
+impl<T> PrettyDebugWithSource for Option<Spanned<T>>
 where
-    Spanned<T>: ToDebug,
+    Spanned<T>: PrettyDebugWithSource,
 {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
         match self {
-            Option::None => write!(f, "nothing"),
-            Option::Some(spanned) => FormatDebug::fmt_debug(spanned, f, source),
+            None => b::description("nothing"),
+            Some(v) => v.pretty_debug(source),
         }
     }
 }
 
 impl<T> HasFallibleSpan for Option<Spanned<T>>
 where
-    Spanned<T>: ToDebug,
+    Spanned<T>: PrettyDebugWithSource,
 {
     fn maybe_span(&self) -> Option<Span> {
         match self {
@@ -588,21 +621,21 @@ where
     }
 }
 
-impl<T> FormatDebug for Option<Tagged<T>>
+impl<T> PrettyDebugWithSource for Option<Tagged<T>>
 where
-    Tagged<T>: ToDebug,
+    Tagged<T>: PrettyDebugWithSource,
 {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
         match self {
-            Option::None => write!(f, "nothing"),
-            Option::Some(item) => FormatDebug::fmt_debug(item, f, source),
+            None => b::description("nothing"),
+            Some(d) => d.pretty_debug(source),
         }
     }
 }
 
 impl<T> HasFallibleSpan for Option<Tagged<T>>
 where
-    Tagged<T>: ToDebug,
+    Tagged<T>: PrettyDebugWithSource,
 {
     fn maybe_span(&self) -> Option<Span> {
         match self {
@@ -614,33 +647,9 @@ where
 
 impl<T> HasSpan for Tagged<T>
 where
-    Tagged<T>: ToDebug,
+    Tagged<T>: PrettyDebugWithSource,
 {
     fn span(&self) -> Span {
         self.tag.span
     }
 }
-
-impl<T: ToDebug> FormatDebug for Vec<T> {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        write!(f, "[ ")?;
-        write!(
-            f,
-            "{}",
-            self.iter().map(|item| item.debug(source)).join(" ")
-        )?;
-        write!(f, " ]")
-    }
-}
-
-impl FormatDebug for String {
-    fn fmt_debug(&self, f: &mut DebugFormatter, _source: &str) -> fmt::Result {
-        write!(f, "{}", self)
-    }
-}
-
-impl FormatDebug for Spanned<String> {
-    fn fmt_debug(&self, f: &mut DebugFormatter, _source: &str) -> fmt::Result {
-        write!(f, "{}", self.item)
-    }
-}

crates/nu-source/src/pretty.rs

@@ -0,0 +1,495 @@
+use crate::term_colored::TermColored;
+use crate::text::Text;
+use derive_new::new;
+use pretty::{BoxAllocator, DocAllocator};
+use std::hash::Hash;
+use termcolor::{Color, ColorSpec};
+
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash)]
+pub enum ShellStyle {
+    Delimiter,
+    Key,
+    Value,
+    Equals,
+    Kind,
+    Keyword,
+    Operator,
+    Variable,
+    Primitive,
+    Opaque,
+    Description,
+    Error,
+}
+
+impl From<ShellAnnotation> for ColorSpec {
+    fn from(ann: ShellAnnotation) -> ColorSpec {
+        match ann.style {
+            ShellStyle::Delimiter => ColorSpec::new()
+                .set_fg(Some(Color::White))
+                .set_intense(false)
+                .clone(),
+            ShellStyle::Key => ColorSpec::new()
+                .set_fg(Some(Color::Black))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Value => ColorSpec::new()
+                .set_fg(Some(Color::White))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Equals => ColorSpec::new()
+                .set_fg(Some(Color::Black))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Kind => ColorSpec::new().set_fg(Some(Color::Cyan)).clone(),
+            ShellStyle::Variable => ColorSpec::new()
+                .set_fg(Some(Color::Green))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Keyword => ColorSpec::new().set_fg(Some(Color::Magenta)).clone(),
+            ShellStyle::Operator => ColorSpec::new().set_fg(Some(Color::Yellow)).clone(),
+            ShellStyle::Primitive => ColorSpec::new()
+                .set_fg(Some(Color::Green))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Opaque => ColorSpec::new()
+                .set_fg(Some(Color::Yellow))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Description => ColorSpec::new()
+                .set_fg(Some(Color::Black))
+                .set_intense(true)
+                .clone(),
+            ShellStyle::Error => ColorSpec::new()
+                .set_fg(Some(Color::Red))
+                .set_intense(true)
+                .clone(),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd, Hash, new)]
+pub struct ShellAnnotation {
+    style: ShellStyle,
+}
+
+impl std::fmt::Debug for ShellAnnotation {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:?}", self.style)
+    }
+}
+
+impl ShellAnnotation {
+    pub fn style(style: impl Into<ShellStyle>) -> ShellAnnotation {
+        ShellAnnotation {
+            style: style.into(),
+        }
+    }
+}
+
+pub type PrettyDebugDoc =
+    pretty::Doc<'static, pretty::BoxDoc<'static, ShellAnnotation>, ShellAnnotation>;
+
+pub type PrettyDebugDocBuilder = pretty::DocBuilder<'static, pretty::BoxAllocator, ShellAnnotation>;
+
+pub use self::DebugDocBuilder as b;
+
+#[derive(Clone, new)]
+pub struct DebugDocBuilder {
+    pub inner: PrettyDebugDocBuilder,
+}
+
+impl PrettyDebug for DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
+        self.clone()
+    }
+}
+
+impl std::ops::Add for DebugDocBuilder {
+    type Output = DebugDocBuilder;
+
+    fn add(self, rhs: DebugDocBuilder) -> DebugDocBuilder {
+        DebugDocBuilder::new(self.inner.append(rhs.inner))
+    }
+}
+
+impl DebugDocBuilder {
+    pub fn from_doc(doc: DebugDoc) -> DebugDocBuilder {
+        DebugDocBuilder {
+            inner: BoxAllocator.nil().append(doc),
+        }
+    }
+
+    pub fn blank() -> DebugDocBuilder {
+        BoxAllocator.nil().into()
+    }
+
+    pub fn delimiter(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Delimiter)
+    }
+
+    pub fn key(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Key)
+    }
+
+    pub fn value(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Value)
+    }
+
+    pub fn as_value(self) -> DebugDocBuilder {
+        self.inner
+            .annotate(ShellAnnotation::style(ShellStyle::Value))
+            .into()
+    }
+
+    pub fn equals() -> DebugDocBuilder {
+        DebugDocBuilder::styled("=", ShellStyle::Equals)
+    }
+
+    pub fn kind(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Kind)
+    }
+
+    pub fn as_kind(self) -> DebugDocBuilder {
+        self.inner
+            .annotate(ShellAnnotation::style(ShellStyle::Kind))
+            .into()
+    }
+
+    pub fn typed(kind: &str, value: DebugDocBuilder) -> DebugDocBuilder {
+        b::delimit("(", b::kind(kind) + b::space() + value.group(), ")").group()
+    }
+
+    pub fn subtyped(
+        kind: &str,
+        subkind: impl std::fmt::Display,
+        value: DebugDocBuilder,
+    ) -> DebugDocBuilder {
+        b::delimit(
+            "(",
+            (b::kind(kind) + b::delimit("[", b::kind(format!("{}", subkind)), "]")).group()
+                + b::space()
+                + value.group(),
+            ")",
+        )
+        .group()
+    }
+
+    pub fn keyword(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Keyword)
+    }
+
+    pub fn var(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Variable)
+    }
+
+    pub fn operator(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Operator)
+    }
+
+    pub fn primitive(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(format!("{}", string), ShellStyle::Primitive)
+    }
+
+    pub fn opaque(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Opaque)
+    }
+
+    pub fn description(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Description)
+    }
+
+    pub fn error(string: impl std::fmt::Display) -> DebugDocBuilder {
+        DebugDocBuilder::styled(string, ShellStyle::Error)
+    }
+
+    pub fn delimit(start: &str, doc: DebugDocBuilder, end: &str) -> DebugDocBuilder {
+        DebugDocBuilder::delimiter(start) + doc + DebugDocBuilder::delimiter(end)
+    }
+
+    pub fn preceded(before: DebugDocBuilder, body: DebugDocBuilder) -> DebugDocBuilder {
+        if body.is_empty() {
+            body
+        } else {
+            before + body
+        }
+    }
+
+    pub fn surrounded_option(
+        before: Option<DebugDocBuilder>,
+        builder: Option<DebugDocBuilder>,
+        after: Option<DebugDocBuilder>,
+    ) -> DebugDocBuilder {
+        match builder {
+            None => DebugDocBuilder::blank(),
+            Some(b) => b::option(before) + b + b::option(after),
+        }
+    }
+
+    pub fn preceded_option(
+        before: Option<DebugDocBuilder>,
+        builder: Option<DebugDocBuilder>,
+    ) -> DebugDocBuilder {
+        DebugDocBuilder::surrounded_option(before, builder, None)
+    }
+
+    pub fn option(builder: Option<DebugDocBuilder>) -> DebugDocBuilder {
+        match builder {
+            None => DebugDocBuilder::blank(),
+            Some(b) => b,
+        }
+    }
+
+    pub fn space() -> DebugDocBuilder {
+        BoxAllocator.space().into()
+    }
+
+    pub fn newline() -> DebugDocBuilder {
+        BoxAllocator.newline().into()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        match &self.inner.1 {
+            pretty::Doc::Nil => true,
+            _ => false,
+        }
+    }
+
+    pub fn or(self, doc: DebugDocBuilder) -> DebugDocBuilder {
+        if self.is_empty() {
+            doc
+        } else {
+            self
+        }
+    }
+
+    pub fn group(self) -> DebugDocBuilder {
+        self.inner.group().into()
+    }
+
+    pub fn nest(self) -> DebugDocBuilder {
+        self.inner.nest(1).group().into()
+    }
+
+    pub fn intersperse_with_source<'a, T: PrettyDebugWithSource + 'a>(
+        list: impl IntoIterator<Item = &'a T>,
+        separator: DebugDocBuilder,
+        source: &str,
+    ) -> DebugDocBuilder {
+        BoxAllocator
+            .intersperse(
+                list.into_iter().filter_map(|item| {
+                    let item = item.pretty_debug(source);
+                    if item.is_empty() {
+                        None
+                    } else {
+                        Some(item)
+                    }
+                }),
+                separator,
+            )
+            .into()
+    }
+
+    pub fn intersperse<T: PrettyDebug>(
+        list: impl IntoIterator<Item = T>,
+        separator: DebugDocBuilder,
+    ) -> DebugDocBuilder {
+        BoxAllocator
+            .intersperse(
+                list.into_iter().filter_map(|item| {
+                    let item = item.pretty();
+                    if item.is_empty() {
+                        None
+                    } else {
+                        Some(item)
+                    }
+                }),
+                separator,
+            )
+            .into()
+    }
+
+    pub fn list(list: impl IntoIterator<Item = DebugDocBuilder>) -> DebugDocBuilder {
+        let mut result: DebugDocBuilder = BoxAllocator.nil().into();
+
+        for item in list {
+            result = result + item;
+        }
+
+        result.into()
+    }
+
+    fn styled(string: impl std::fmt::Display, style: ShellStyle) -> DebugDocBuilder {
+        BoxAllocator
+            .text(string.to_string())
+            .annotate(ShellAnnotation::style(style))
+            .into()
+    }
+}
+
+impl std::ops::Deref for DebugDocBuilder {
+    type Target = PrettyDebugDocBuilder;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd, new)]
+pub struct DebugDoc {
+    pub inner: PrettyDebugDoc,
+}
+
+pub trait PrettyDebugWithSource: Sized {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder;
+
+    // This is a transitional convenience method
+    fn debug(&self, source: impl Into<Text>) -> String
+    where
+        Self: Clone,
+    {
+        self.clone().debuggable(source).display()
+    }
+
+    fn debuggable(self, source: impl Into<Text>) -> DebuggableWithSource<Self> {
+        DebuggableWithSource {
+            inner: self,
+            source: source.into(),
+        }
+    }
+}
+
+impl<T: PrettyDebug> PrettyDebugWithSource for T {
+    fn pretty_debug(&self, _source: &str) -> DebugDocBuilder {
+        self.pretty()
+    }
+}
+
+pub struct DebuggableWithSource<T: PrettyDebugWithSource> {
+    inner: T,
+    source: Text,
+}
+
+impl<T> PrettyDebug for DebuggableWithSource<T>
+where
+    T: PrettyDebugWithSource,
+{
+    fn pretty(&self) -> DebugDocBuilder {
+        self.inner.pretty_debug(&self.source)
+    }
+}
+
+impl PrettyDebug for DebugDoc {
+    fn pretty(&self) -> DebugDocBuilder {
+        DebugDocBuilder::new(BoxAllocator.nil().append(self.inner.clone()))
+    }
+}
+
+pub trait PrettyDebug {
+    fn pretty(&self) -> DebugDocBuilder;
+
+    fn to_doc(&self) -> DebugDoc {
+        DebugDoc::new(self.pretty().into())
+    }
+
+    fn pretty_doc(&self) -> PrettyDebugDoc {
+        let builder = self.pretty();
+        builder.inner.into()
+    }
+
+    fn pretty_builder(&self) -> PrettyDebugDocBuilder {
+        let doc = self.pretty();
+        doc.inner
+    }
+
+    /// A convenience method that prints out the document without colors in
+    /// 70 columns. Generally, you should use plain_string or colored_string
+    /// if possible, but display() can be useful for trace lines and things
+    /// like that, where you don't have control over the terminal.
+    fn display(&self) -> String {
+        self.plain_string(70)
+    }
+
+    fn plain_string(&self, width: usize) -> String {
+        let doc = self.pretty_doc();
+        let mut buffer = termcolor::Buffer::no_color();
+
+        doc.render_raw(width, &mut TermColored::new(&mut buffer))
+            .unwrap();
+
+        String::from_utf8_lossy(buffer.as_slice()).to_string()
+    }
+
+    fn colored_string(&self, width: usize) -> String {
+        let doc = self.pretty_doc();
+        let mut buffer = termcolor::Buffer::ansi();
+
+        doc.render_raw(width, &mut TermColored::new(&mut buffer))
+            .unwrap();
+
+        String::from_utf8_lossy(buffer.as_slice()).to_string()
+    }
+}
+
+impl Into<DebugDocBuilder> for PrettyDebugDocBuilder {
+    fn into(self) -> DebugDocBuilder {
+        DebugDocBuilder { inner: self }
+    }
+}
+
+impl std::ops::Deref for DebugDoc {
+    type Target = PrettyDebugDoc;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl From<DebugDoc> for PrettyDebugDoc {
+    fn from(input: DebugDoc) -> PrettyDebugDoc {
+        input.inner
+    }
+}
+
+impl Into<PrettyDebugDoc> for DebugDocBuilder {
+    fn into(self) -> PrettyDebugDoc {
+        self.inner.into()
+    }
+}
+
+fn hash_doc<H: std::hash::Hasher>(doc: &PrettyDebugDoc, state: &mut H) {
+    match doc {
+        pretty::Doc::Nil => 0u8.hash(state),
+        pretty::Doc::Append(a, b) => {
+            1u8.hash(state);
+            hash_doc(&*a, state);
+            hash_doc(&*b, state);
+        }
+        pretty::Doc::Group(a) => {
+            2u8.hash(state);
+            hash_doc(&*a, state);
+        }
+        pretty::Doc::Nest(a, b) => {
+            3u8.hash(state);
+            a.hash(state);
+            hash_doc(&*b, state);
+        }
+        pretty::Doc::Space => 4u8.hash(state),
+        pretty::Doc::Newline => 5u8.hash(state),
+        pretty::Doc::Text(t) => {
+            6u8.hash(state);
+            t.hash(state);
+        }
+        pretty::Doc::Annotated(a, b) => {
+            7u8.hash(state);
+            a.hash(state);
+            hash_doc(&*b, state);
+        }
+    }
+}
+
+impl std::hash::Hash for DebugDoc {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        hash_doc(&self.inner, state);
+    }
+}

crates/nu-source/src/term_colored.rs

@@ -0,0 +1,51 @@
+use crate::pretty::ShellAnnotation;
+use pretty::{Render, RenderAnnotated};
+use std::io;
+use termcolor::WriteColor;
+
+pub struct TermColored<'a, W> {
+    color_stack: Vec<ShellAnnotation>,
+    upstream: &'a mut W,
+}
+
+impl<'a, W> TermColored<'a, W> {
+    pub fn new(upstream: &'a mut W) -> TermColored<'a, W> {
+        TermColored {
+            color_stack: Vec::new(),
+            upstream,
+        }
+    }
+}
+
+impl<'a, W> Render for TermColored<'a, W>
+where
+    W: io::Write,
+{
+    type Error = io::Error;
+
+    fn write_str(&mut self, s: &str) -> io::Result<usize> {
+        self.upstream.write(s.as_bytes())
+    }
+
+    fn write_str_all(&mut self, s: &str) -> io::Result<()> {
+        self.upstream.write_all(s.as_bytes())
+    }
+}
+
+impl<'a, W> RenderAnnotated<ShellAnnotation> for TermColored<'a, W>
+where
+    W: WriteColor,
+{
+    fn push_annotation(&mut self, ann: &ShellAnnotation) -> Result<(), Self::Error> {
+        self.color_stack.push(*ann);
+        self.upstream.set_color(&(*ann).into())
+    }
+
+    fn pop_annotation(&mut self) -> Result<(), Self::Error> {
+        self.color_stack.pop();
+        match self.color_stack.last() {
+            Some(previous) => self.upstream.set_color(&(*previous).into()),
+            None => self.upstream.reset(),
+        }
+    }
+}

crates/nu-source/src/text.rs

@@ -74,6 +74,12 @@ impl From<&str> for Text {
     }
 }
 
+impl From<&Text> for Text {
+    fn from(text: &Text) -> Self {
+        text.clone()
+    }
+}
+
 impl std::borrow::Borrow<str> for Text {
     fn borrow(&self) -> &str {
         &*self

crates/nu-source/src/tracable.rs

@@ -0,0 +1,32 @@
+use derive_new::new;
+use nom_locate::LocatedSpanEx;
+use nom_tracable::{HasTracableInfo, TracableInfo};
+
+pub type NomSpan<'a> = LocatedSpanEx<&'a str, TracableContext>;
+
+#[derive(Debug, Clone, Copy, PartialEq, new)]
+pub struct TracableContext {
+    pub(crate) info: TracableInfo,
+}
+
+impl HasTracableInfo for TracableContext {
+    fn get_tracable_info(&self) -> TracableInfo {
+        self.info
+    }
+
+    fn set_tracable_info(self, info: TracableInfo) -> Self {
+        TracableContext { info }
+    }
+}
+
+impl std::ops::Deref for TracableContext {
+    type Target = TracableInfo;
+
+    fn deref(&self) -> &TracableInfo {
+        &self.info
+    }
+}
+
+pub fn nom_input(s: &str) -> NomSpan<'_> {
+    LocatedSpanEx::new_extra(s, TracableContext::new(TracableInfo::new()))
+}

src/cli.rs

@@ -1,13 +1,15 @@
 use crate::commands::classified::{
-    ClassifiedCommand, ClassifiedInputStream, ClassifiedPipeline, ExternalCommand, InternalCommand,
-    StreamNext,
+    ClassifiedCommand, ClassifiedInputStream, ClassifiedPipeline, ExternalArg, ExternalArgs,
+    ExternalCommand, InternalCommand, StreamNext,
 };
 use crate::commands::plugin::JsonRpc;
 use crate::commands::plugin::{PluginCommand, PluginSink};
 use crate::commands::whole_stream_command;
 use crate::context::Context;
-use crate::data::config;
-use crate::data::Value;
+use crate::data::{
+    base::{UntaggedValue, Value},
+    config,
+};
 pub(crate) use crate::errors::ShellError;
 #[cfg(not(feature = "starship-prompt"))]
 use crate::git::current_branch;
@@ -19,6 +21,7 @@ use crate::parser::{
     TokenNode,
 };
 use crate::prelude::*;
+use nu_source::{Spanned, Tagged};
 
 use log::{debug, log_enabled, trace};
 use rustyline::error::ReadlineError;
@@ -381,7 +384,7 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
 
         let edit_mode = config::config(Tag::unknown())?
             .get("edit_mode")
-            .map(|s| match s.as_string().unwrap().as_ref() {
+            .map(|s| match s.value.expect_string() {
                 "vi" => EditMode::Vi,
                 "emacs" => EditMode::Emacs,
                 _ => EditMode::Emacs,
@@ -448,7 +451,7 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
             LineResult::CtrlC => {
                 let config_ctrlc_exit = config::config(Tag::unknown())?
                     .get("ctrlc_exit")
-                    .map(|s| match s.as_string().unwrap().as_ref() {
+                    .map(|s| match s.value.expect_string() {
                         "true" => true,
                         _ => false,
                     })
@@ -501,8 +504,8 @@ fn set_env_from_config() {
         let value = config.get("env");
 
         match value {
-            Some(Tagged {
-                item: Value::Row(r),
+            Some(Value {
+                value: UntaggedValue::Row(r),
                 ..
             }) => {
                 for (k, v) in &r.entries {
@@ -524,8 +527,8 @@ fn set_env_from_config() {
 
         match value {
             Some(value) => match value {
-                Tagged {
-                    item: Value::Table(table),
+                Value {
+                    value: UntaggedValue::Table(table),
                     ..
                 } => {
                     let mut paths = vec![];
@@ -583,11 +586,11 @@ async fn process_line(readline: Result<String, ReadlineError>, ctx: &mut Context
                 Err(err) => return LineResult::Error(line.to_string(), err),
             };
 
-            match pipeline.commands.last() {
+            match pipeline.commands.list.last() {
                 Some(ClassifiedCommand::External(_)) => {}
                 _ => pipeline
                     .commands
-                    .item
+                    .list
                     .push(ClassifiedCommand::Internal(InternalCommand {
                         name: "autoview".to_string(),
                         name_tag: Tag::unknown(),
@@ -595,13 +598,13 @@ async fn process_line(readline: Result<String, ReadlineError>, ctx: &mut Context
                             Box::new(hir::Expression::synthetic_string("autoview")),
                             None,
                             None,
-                        )
-                        .spanned_unknown(),
+                            Span::unknown(),
+                        ),
                     })),
             }
 
             let mut input = ClassifiedInputStream::new();
-            let mut iter = pipeline.commands.item.into_iter().peekable();
+            let mut iter = pipeline.commands.list.into_iter().peekable();
 
             // Check the config to see if we need to update the path
             // TODO: make sure config is cached so we don't path this load every call
@@ -659,8 +662,8 @@ async fn process_line(readline: Result<String, ReadlineError>, ctx: &mut Context
                                 let mut output_stream: OutputStream = val.into();
                                 loop {
                                     match output_stream.try_next().await {
-                                        Ok(Some(ReturnSuccess::Value(Tagged {
-                                            item: Value::Error(e),
+                                        Ok(Some(ReturnSuccess::Value(Value {
+                                            value: UntaggedValue::Error(e),
                                             ..
                                         }))) => {
                                             return LineResult::Error(line.to_string(), e);
@@ -723,7 +726,7 @@ fn classify_pipeline(
     source: &Text,
 ) -> Result<ClassifiedPipeline, ShellError> {
     let mut pipeline_list = vec![pipeline.clone()];
-    let mut iterator = TokensIterator::all(&mut pipeline_list, pipeline.span());
+    let mut iterator = TokensIterator::all(&mut pipeline_list, source.clone(), pipeline.span());
 
     let result = expand_syntax(
         &PipelineShape,
@@ -749,19 +752,21 @@ pub(crate) fn external_command(
     context: &ExpandContext,
     name: Tagged<&str>,
 ) -> Result<ClassifiedCommand, ParseError> {
-    let Spanned { item, span } = expand_syntax(&ExternalTokensShape, tokens, context)?;
+    let Spanned { item, span } = expand_syntax(&ExternalTokensShape, tokens, context)?.tokens;
 
     Ok(ClassifiedCommand::External(ExternalCommand {
         name: name.to_string(),
         name_tag: name.tag(),
-        args: item
-            .iter()
-            .map(|x| Tagged {
-                tag: x.span.into(),
-                item: x.item.clone(),
-            })
-            .collect::<Vec<_>>()
-            .spanned(span),
+        args: ExternalArgs {
+            list: item
+                .iter()
+                .map(|x| ExternalArg {
+                    tag: x.span.into(),
+                    arg: x.item.clone(),
+                })
+                .collect(),
+            span,
+        },
     }))
 }
 

src/commands/append.rs

@@ -5,7 +5,7 @@ use crate::prelude::*;
 
 #[derive(Deserialize)]
 struct AppendArgs {
-    row: Tagged<Value>,
+    row: Value,
 }
 
 pub struct Append;
@@ -40,7 +40,7 @@ fn append(
     AppendArgs { row }: AppendArgs,
     RunnableContext { input, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
-    let mut after: VecDeque<Tagged<Value>> = VecDeque::new();
+    let mut after: VecDeque<Value> = VecDeque::new();
     after.push_back(row);
 
     Ok(OutputStream::from_input(input.values.chain(after)))

src/commands/autoview.rs

@@ -93,9 +93,9 @@ pub fn autoview(
 
                                 let raw = raw.clone();
 
-                                let input: Vec<Tagged<Value>> = new_input.into();
+                                let input: Vec<Value> = new_input.into();
 
-                                if input.len() > 0 && input.iter().all(|value| value.is_error()) {
+                                if input.len() > 0 && input.iter().all(|value| value.value.is_error()) {
                                     let first = &input[0];
 
                                     let mut host = context.host.clone();
@@ -107,7 +107,7 @@ pub fn autoview(
                                         Ok(val) => val
                                     };
 
-                                    crate::cli::print_err(first.item.expect_error(), &*host, &context.source);
+                                    crate::cli::print_err(first.value.expect_error(), &*host, &context.source);
                                     return;
                                 }
 
@@ -131,30 +131,30 @@ pub fn autoview(
                     _ => {
                         if let ReturnSuccess::Value(x) = x {
                             match x {
-                                Tagged {
-                                    item: Value::Primitive(Primitive::String(ref s)),
+                                Value {
+                                    value: UntaggedValue::Primitive(Primitive::String(ref s)),
                                     tag: Tag { anchor, span },
                                 } if anchor.is_some() => {
                                     if let Some(text) = text {
                                         let mut stream = VecDeque::new();
-                                        stream.push_back(Value::string(s).tagged(Tag { anchor, span }));
+                                        stream.push_back(UntaggedValue::string(s).into_value(Tag { anchor, span }));
                                         let result = text.run(raw.with_input(stream.into()), &context.commands);
                                         result.collect::<Vec<_>>().await;
                                     } else {
                                         outln!("{}", s);
                                     }
                                 }
-                                Tagged {
-                                    item: Value::Primitive(Primitive::String(s)),
+                                Value {
+                                    value: UntaggedValue::Primitive(Primitive::String(s)),
                                     ..
                                 } => {
                                     outln!("{}", s);
                                 }
 
-                                Tagged { item: Value::Primitive(Primitive::Binary(ref b)), .. } => {
+                                Value { value: UntaggedValue::Primitive(Primitive::Binary(ref b)), .. } => {
                                     if let Some(binary) = binary {
                                         let mut stream = VecDeque::new();
-                                        stream.push_back(x.clone());
+                                        stream.push_back(x);
                                         let result = binary.run(raw.with_input(stream.into()), &context.commands);
                                         result.collect::<Vec<_>>().await;
                                     } else {
@@ -163,13 +163,13 @@ pub fn autoview(
                                     }
                                 }
 
-                                Tagged { item: Value::Error(e), .. } => {
+                                Value { value: UntaggedValue::Error(e), .. } => {
                                     yield Err(e);
                                 }
-                                Tagged { item: ref item, .. } => {
+                                Value { value: ref item, .. } => {
                                     if let Some(table) = table {
                                         let mut stream = VecDeque::new();
-                                        stream.push_back(x.clone());
+                                        stream.push_back(x);
                                         let result = table.run(raw.with_input(stream.into()), &context.commands);
                                         result.collect::<Vec<_>>().await;
                                     } else {
@@ -188,7 +188,7 @@ pub fn autoview(
 
         // Needed for async_stream to type check
         if false {
-            yield ReturnSuccess::value(Value::nothing().tagged_unknown());
+            yield ReturnSuccess::value(UntaggedValue::nothing().into_untagged_value());
         }
     }))
 }

src/commands/classified.rs

@@ -4,9 +4,8 @@ use bytes::{BufMut, BytesMut};
 use derive_new::new;
 use futures::stream::StreamExt;
 use futures_codec::{Decoder, Encoder, Framed};
-use itertools::Itertools;
 use log::{log_enabled, trace};
-use std::fmt;
+use nu_source::PrettyDebug;
 use std::io::{Error, ErrorKind};
 use subprocess::Exec;
 
@@ -54,7 +53,7 @@ pub(crate) struct ClassifiedInputStream {
 impl ClassifiedInputStream {
     pub(crate) fn new() -> ClassifiedInputStream {
         ClassifiedInputStream {
-            objects: vec![Value::nothing().tagged(Tag::unknown())].into(),
+            objects: vec![UntaggedValue::nothing().into_value(Tag::unknown())].into(),
             stdin: None,
         }
     }
@@ -75,16 +74,42 @@ impl ClassifiedInputStream {
 }
 
 #[derive(Debug, Clone)]
-pub(crate) struct ClassifiedPipeline {
-    pub(crate) commands: Spanned<Vec<ClassifiedCommand>>,
+pub struct Commands {
+    pub list: Vec<ClassifiedCommand>,
+    pub span: Span,
 }
 
-impl FormatDebug for ClassifiedPipeline {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        f.say_str(
-            "classified pipeline",
-            self.commands.iter().map(|c| c.debug(source)).join(" | "),
+impl std::ops::Deref for Commands {
+    type Target = [ClassifiedCommand];
+
+    fn deref(&self) -> &Self::Target {
+        &self.list
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ClassifiedPipeline {
+    pub commands: Commands,
+}
+
+impl ClassifiedPipeline {
+    pub fn commands(list: Vec<ClassifiedCommand>, span: impl Into<Span>) -> ClassifiedPipeline {
+        ClassifiedPipeline {
+            commands: Commands {
+                list,
+                span: span.into(),
+            },
+        }
+    }
+}
+
+impl PrettyDebugWithSource for ClassifiedPipeline {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
+        b::intersperse(
+            self.commands.iter().map(|c| c.pretty_debug(source)),
+            b::operator(" | "),
         )
+        .or(b::delimit("<", b::description("empty pipeline"), ">"))
     }
 }
 
@@ -95,22 +120,22 @@ impl HasSpan for ClassifiedPipeline {
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
-pub(crate) enum ClassifiedCommand {
+pub enum ClassifiedCommand {
     #[allow(unused)]
     Expr(TokenNode),
-    Internal(InternalCommand),
     #[allow(unused)]
-    Dynamic(Spanned<hir::Call>),
+    Dynamic(hir::Call),
+    Internal(InternalCommand),
     External(ExternalCommand),
 }
 
-impl FormatDebug for ClassifiedCommand {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
+impl PrettyDebugWithSource for ClassifiedCommand {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
         match self {
-            ClassifiedCommand::Expr(expr) => expr.fmt_debug(f, source),
-            ClassifiedCommand::Internal(internal) => internal.fmt_debug(f, source),
-            ClassifiedCommand::Dynamic(dynamic) => dynamic.fmt_debug(f, source),
-            ClassifiedCommand::External(external) => external.fmt_debug(f, source),
+            ClassifiedCommand::Expr(token) => b::typed("command", token.pretty_debug(source)),
+            ClassifiedCommand::Dynamic(call) => b::typed("command", call.pretty_debug(source)),
+            ClassifiedCommand::Internal(internal) => internal.pretty_debug(source),
+            ClassifiedCommand::External(external) => external.pretty_debug(source),
         }
     }
 }
@@ -127,10 +152,19 @@ impl HasSpan for ClassifiedCommand {
 }
 
 #[derive(new, Debug, Clone, Eq, PartialEq)]
-pub(crate) struct InternalCommand {
+pub struct InternalCommand {
     pub(crate) name: String,
     pub(crate) name_tag: Tag,
-    pub(crate) args: Spanned<hir::Call>,
+    pub(crate) args: hir::Call,
+}
+
+impl PrettyDebugWithSource for InternalCommand {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
+        b::typed(
+            "internal command",
+            b::description(&self.name) + b::space() + self.args.pretty_debug(source),
+        )
+    }
 }
 
 impl HasSpan for InternalCommand {
@@ -141,12 +175,6 @@ impl HasSpan for InternalCommand {
     }
 }
 
-impl FormatDebug for InternalCommand {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        f.say("internal", self.args.debug(source))
-    }
-}
-
 #[derive(new, Debug, Eq, PartialEq)]
 pub(crate) struct DynamicCommand {
     pub(crate) args: hir::Call,
@@ -165,21 +193,15 @@ impl InternalCommand {
             trace!(target: "nu::run::internal", "{}", self.args.debug(&source));
         }
 
-        let objects: InputStream = trace_stream!(target: "nu::trace_stream::internal", source: source, "input" = input.objects);
+        let objects: InputStream =
+            trace_stream!(target: "nu::trace_stream::internal", "input" = input.objects);
 
         let command = context.expect_command(&self.name);
 
-        let result = {
-            context.run_command(
-                command,
-                self.name_tag.clone(),
-                self.args.item,
-                &source,
-                objects,
-            )
-        };
+        let result =
+            { context.run_command(command, self.name_tag.clone(), self.args, &source, objects) };
 
-        let result = trace_out_stream!(target: "nu::trace_stream::internal", source: source, "output" = result);
+        let result = trace_out_stream!(target: "nu::trace_stream::internal", "output" = result);
         let mut result = result.values;
         let mut context = context.clone();
 
@@ -200,13 +222,13 @@ impl InternalCommand {
                         }
                         CommandAction::EnterHelpShell(value) => {
                             match value {
-                                Tagged {
-                                    item: Value::Primitive(Primitive::String(cmd)),
+                                Value {
+                                    value: UntaggedValue::Primitive(Primitive::String(cmd)),
                                     tag,
                                 } => {
                                     context.shell_manager.insert_at_current(Box::new(
                                         HelpShell::for_command(
-                                            Value::string(cmd).tagged(tag),
+                                            UntaggedValue::string(cmd).into_value(tag),
                                             &context.registry(),
                                         ).unwrap(),
                                     ));
@@ -250,7 +272,7 @@ impl InternalCommand {
                     Ok(ReturnSuccess::DebugValue(v)) => {
                         yielded = true;
 
-                        let doc = v.item.pretty_doc();
+                        let doc = PrettyDebug::pretty_doc(&v);
                         let mut buffer = termcolor::Buffer::ansi();
 
                         doc.render_raw(
@@ -260,7 +282,7 @@ impl InternalCommand {
 
                         let value = String::from_utf8_lossy(buffer.as_slice());
 
-                        yield Ok(Value::string(value).tagged_unknown())
+                        yield Ok(UntaggedValue::string(value).into_untagged_value())
                     }
 
                     Err(err) => {
@@ -276,23 +298,60 @@ impl InternalCommand {
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
-pub(crate) struct ExternalCommand {
+pub struct ExternalArg {
+    pub arg: String,
+    pub tag: Tag,
+}
+
+impl std::ops::Deref for ExternalArg {
+    type Target = str;
+
+    fn deref(&self) -> &str {
+        &self.arg
+    }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct ExternalArgs {
+    pub list: Vec<ExternalArg>,
+    pub span: Span,
+}
+
+impl ExternalArgs {
+    pub fn iter(&self) -> impl Iterator<Item = &ExternalArg> {
+        self.list.iter()
+    }
+}
+
+impl std::ops::Deref for ExternalArgs {
+    type Target = [ExternalArg];
+
+    fn deref(&self) -> &[ExternalArg] {
+        &self.list
+    }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct ExternalCommand {
     pub(crate) name: String,
 
     pub(crate) name_tag: Tag,
-    pub(crate) args: Spanned<Vec<Tagged<String>>>,
+    pub(crate) args: ExternalArgs,
 }
 
-impl FormatDebug for ExternalCommand {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        write!(f, "{}", self.name)?;
-
-        if self.args.item.len() > 0 {
-            write!(f, " ")?;
-            write!(f, "{}", self.args.iter().map(|i| i.debug(source)).join(" "))?;
-        }
-
-        Ok(())
+impl PrettyDebug for ExternalCommand {
+    fn pretty(&self) -> DebugDocBuilder {
+        b::typed(
+            "external command",
+            b::description(&self.name)
+                + b::preceded(
+                    b::space(),
+                    b::intersperse(
+                        self.args.iter().map(|a| b::primitive(format!("{}", a.arg))),
+                        b::space(),
+                    ),
+                ),
+        )
     }
 }
 
@@ -317,13 +376,13 @@ impl ExternalCommand {
         stream_next: StreamNext,
     ) -> Result<ClassifiedInputStream, ShellError> {
         let stdin = input.stdin;
-        let inputs: Vec<Tagged<Value>> = input.objects.into_vec().await;
+        let inputs: Vec<Value> = input.objects.into_vec().await;
 
         trace!(target: "nu::run::external", "-> {}", self.name);
         trace!(target: "nu::run::external", "inputs = {:?}", inputs);
 
         let mut arg_string = format!("{}", self.name);
-        for arg in &self.args.item {
+        for arg in self.args.iter() {
             arg_string.push_str(&arg);
         }
 
@@ -334,13 +393,13 @@ impl ExternalCommand {
             let input_strings = inputs
                 .iter()
                 .map(|i| {
-                    i.as_string().map_err(|_| {
-                        let arg = self.args.iter().find(|arg| arg.item.contains("$it"));
+                    i.as_string().map(|s| s.to_string()).map_err(|_| {
+                        let arg = self.args.iter().find(|arg| arg.contains("$it"));
                         if let Some(arg) = arg {
                             ShellError::labeled_error(
                                 "External $it needs string data",
                                 "given row instead of string data",
-                                arg.tag(),
+                                &arg.tag,
                             )
                         } else {
                             ShellError::labeled_error(
@@ -368,7 +427,7 @@ impl ExternalCommand {
             process = Exec::shell(itertools::join(commands, " && "))
         } else {
             process = Exec::cmd(&self.name);
-            for arg in &self.args.item {
+            for arg in self.args.iter() {
                 let arg_chars: Vec<_> = arg.chars().collect();
                 if arg_chars.len() > 1
                     && arg_chars[0] == '"'
@@ -378,7 +437,7 @@ impl ExternalCommand {
                     let new_arg: String = arg_chars[1..arg_chars.len() - 1].iter().collect();
                     process = process.arg(new_arg);
                 } else {
-                    process = process.arg(arg.item.clone());
+                    process = process.arg(arg.arg.clone());
                 }
             }
         }
@@ -435,10 +494,11 @@ impl ExternalCommand {
                     let stdout = popen.stdout.take().unwrap();
                     let file = futures::io::AllowStdIo::new(stdout);
                     let stream = Framed::new(file, LinesCodec {});
-                    let stream =
-                        stream.map(move |line| Value::string(line.unwrap()).tagged(&name_tag));
+                    let stream = stream.map(move |line| {
+                        UntaggedValue::string(line.unwrap()).into_value(&name_tag)
+                    });
                     Ok(ClassifiedInputStream::from_input_stream(
-                        stream.boxed() as BoxStream<'static, Tagged<Value>>
+                        stream.boxed() as BoxStream<'static, Value>
                     ))
                 }
             }

src/commands/clip.rs

@@ -40,7 +40,7 @@ pub mod clipboard {
         RunnableContext { input, name, .. }: RunnableContext,
     ) -> Result<OutputStream, ShellError> {
         let stream = async_stream! {
-            let values: Vec<Tagged<Value>> = input.values.collect().await;
+            let values: Vec<Value> = input.values.collect().await;
 
             let mut clip_stream = inner_clip(values, name).await;
             while let Some(value) = clip_stream.next().await {
@@ -53,7 +53,7 @@ pub mod clipboard {
         Ok(OutputStream::from(stream))
     }
 
-    async fn inner_clip(input: Vec<Tagged<Value>>, name: Tag) -> OutputStream {
+    async fn inner_clip(input: Vec<Value>, name: Tag) -> OutputStream {
         let mut clip_context: ClipboardContext = ClipboardProvider::new().unwrap();
         let mut new_copy_data = String::new();
 

src/commands/command.rs

@@ -7,7 +7,6 @@ use crate::prelude::*;
 use derive_new::new;
 use getset::Getters;
 use serde::{Deserialize, Serialize};
-use std::fmt;
 use std::ops::Deref;
 use std::path::PathBuf;
 use std::sync::atomic::AtomicBool;
@@ -19,12 +18,6 @@ pub struct UnevaluatedCallInfo {
     pub name_tag: Tag,
 }
 
-impl FormatDebug for UnevaluatedCallInfo {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        self.args.fmt_debug(f, source)
-    }
-}
-
 impl UnevaluatedCallInfo {
     pub fn evaluate(
         self,
@@ -85,7 +78,7 @@ pub struct RawCommandArgs {
 }
 
 impl RawCommandArgs {
-    pub fn with_input(self, input: Vec<Tagged<Value>>) -> CommandArgs {
+    pub fn with_input(self, input: Vec<Value>) -> CommandArgs {
         CommandArgs {
             host: self.host,
             ctrl_c: self.ctrl_c,
@@ -106,12 +99,6 @@ impl std::fmt::Debug for CommandArgs {
     }
 }
 
-impl FormatDebug for CommandArgs {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        self.call_info.fmt_debug(f, source)
-    }
-}
-
 impl CommandArgs {
     pub fn evaluate_once(
         self,
@@ -366,11 +353,11 @@ impl EvaluatedCommandArgs {
         &self.call_info.args
     }
 
-    pub fn nth(&self, pos: usize) -> Option<&Tagged<Value>> {
+    pub fn nth(&self, pos: usize) -> Option<&Value> {
         self.call_info.args.nth(pos)
     }
 
-    pub fn expect_nth(&self, pos: usize) -> Result<&Tagged<Value>, ShellError> {
+    pub fn expect_nth(&self, pos: usize) -> Result<&Value, ShellError> {
         self.call_info.args.expect_nth(pos)
     }
 
@@ -378,11 +365,11 @@ impl EvaluatedCommandArgs {
         self.call_info.args.len()
     }
 
-    pub fn get(&self, name: &str) -> Option<&Tagged<Value>> {
+    pub fn get(&self, name: &str) -> Option<&Value> {
         self.call_info.args.get(name)
     }
 
-    pub fn slice_from(&self, from: usize) -> Vec<Tagged<Value>> {
+    pub fn slice_from(&self, from: usize) -> Vec<Value> {
         let positional = &self.call_info.args.positional;
 
         match positional {
@@ -402,55 +389,50 @@ pub enum CommandAction {
     Exit,
     Error(ShellError),
     EnterShell(String),
-    EnterValueShell(Tagged<Value>),
-    EnterHelpShell(Tagged<Value>),
+    EnterValueShell(Value),
+    EnterHelpShell(Value),
     PreviousShell,
     NextShell,
     LeaveShell,
 }
 
-impl FormatDebug for CommandAction {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
+impl PrettyDebug for CommandAction {
+    fn pretty(&self) -> DebugDocBuilder {
         match self {
-            CommandAction::ChangePath(s) => write!(f, "action:change-path={}", s),
-            CommandAction::Exit => write!(f, "action:exit"),
-            CommandAction::Error(_) => write!(f, "action:error"),
-            CommandAction::EnterShell(s) => write!(f, "action:enter-shell={}", s),
-            CommandAction::EnterValueShell(t) => {
-                write!(f, "action:enter-value-shell={}", t.debug(source))
-            }
-            CommandAction::EnterHelpShell(t) => {
-                write!(f, "action:enter-help-shell={}", t.debug(source))
-            }
-            CommandAction::PreviousShell => write!(f, "action:previous-shell"),
-            CommandAction::NextShell => write!(f, "action:next-shell"),
-            CommandAction::LeaveShell => write!(f, "action:leave-shell"),
+            CommandAction::ChangePath(path) => b::typed("change path", b::description(path)),
+            CommandAction::Exit => b::description("exit"),
+            CommandAction::Error(_) => b::error("error"),
+            CommandAction::EnterShell(s) => b::typed("enter shell", b::description(s)),
+            CommandAction::EnterValueShell(v) => b::typed("enter value shell", v.pretty()),
+            CommandAction::EnterHelpShell(v) => b::typed("enter help shell", v.pretty()),
+            CommandAction::PreviousShell => b::description("previous shell"),
+            CommandAction::NextShell => b::description("next shell"),
+            CommandAction::LeaveShell => b::description("leave shell"),
         }
     }
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub enum ReturnSuccess {
-    Value(Tagged<Value>),
-    DebugValue(Tagged<Value>),
+    Value(Value),
+    DebugValue(Value),
     Action(CommandAction),
 }
 
-pub type ReturnValue = Result<ReturnSuccess, ShellError>;
-
-impl FormatDebug for ReturnValue {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
+impl PrettyDebug for ReturnSuccess {
+    fn pretty(&self) -> DebugDocBuilder {
         match self {
-            Err(err) => write!(f, "{}", err.debug(source)),
-            Ok(ReturnSuccess::Value(v)) => write!(f, "{}", v.debug(source)),
-            Ok(ReturnSuccess::DebugValue(v)) => v.fmt_debug(f, source),
-            Ok(ReturnSuccess::Action(a)) => write!(f, "{}", a.debug(source)),
+            ReturnSuccess::Value(value) => b::typed("value", value.pretty()),
+            ReturnSuccess::DebugValue(value) => b::typed("debug value", value.pretty()),
+            ReturnSuccess::Action(action) => b::typed("action", action.pretty()),
         }
     }
 }
 
-impl From<Tagged<Value>> for ReturnValue {
-    fn from(input: Tagged<Value>) -> ReturnValue {
+pub type ReturnValue = Result<ReturnSuccess, ShellError>;
+
+impl From<Value> for ReturnValue {
+    fn from(input: Value) -> ReturnValue {
         Ok(ReturnSuccess::Value(input))
     }
 }
@@ -460,11 +442,11 @@ impl ReturnSuccess {
         Ok(ReturnSuccess::Action(CommandAction::ChangePath(path)))
     }
 
-    pub fn value(input: impl Into<Tagged<Value>>) -> ReturnValue {
+    pub fn value(input: impl Into<Value>) -> ReturnValue {
         Ok(ReturnSuccess::Value(input.into()))
     }
 
-    pub fn debug_value(input: impl Into<Tagged<Value>>) -> ReturnValue {
+    pub fn debug_value(input: impl Into<Value>) -> ReturnValue {
         Ok(ReturnSuccess::DebugValue(input.into()))
     }
 
@@ -521,7 +503,7 @@ pub trait PerItemCommand: Send + Sync {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        input: Tagged<Value>,
+        input: Value,
     ) -> Result<OutputStream, ShellError>;
 
     fn is_binary(&self) -> bool {
@@ -534,6 +516,29 @@ pub enum Command {
     PerItem(Arc<dyn PerItemCommand>),
 }
 
+impl PrettyDebugWithSource for Command {
+    fn pretty_debug(&self, source: &str) -> DebugDocBuilder {
+        match self {
+            Command::WholeStream(command) => b::typed(
+                "whole stream command",
+                b::description(command.name())
+                    + b::space()
+                    + b::equals()
+                    + b::space()
+                    + command.signature().pretty_debug(source),
+            ),
+            Command::PerItem(command) => b::typed(
+                "per item command",
+                b::description(command.name())
+                    + b::space()
+                    + b::equals()
+                    + b::space()
+                    + command.signature().pretty_debug(source),
+            ),
+        }
+    }
+}
+
 impl std::fmt::Debug for Command {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {

src/commands/compact.rs

@@ -1,8 +1,10 @@
 use crate::commands::WholeStreamCommand;
+use crate::data::base::UntaggedValue;
 use crate::errors::ShellError;
 use crate::parser::registry::{CommandRegistry, Signature};
 use crate::prelude::*;
 use futures::stream::StreamExt;
+use nu_source::Tagged;
 
 pub struct Compact;
 
@@ -42,8 +44,8 @@ pub fn compact(
             item.is_some()
         } else {
             match item {
-                Tagged {
-                    item: Value::Row(ref r),
+                Value {
+                    value: UntaggedValue::Row(ref r),
                     ..
                 } => columns
                     .iter()

src/commands/config.rs

@@ -4,6 +4,7 @@ use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::{self};
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct Config;
@@ -11,7 +12,7 @@ pub struct Config;
 #[derive(Deserialize)]
 pub struct ConfigArgs {
     load: Option<Tagged<PathBuf>>,
-    set: Option<(Tagged<String>, Tagged<Value>)>,
+    set: Option<(Tagged<String>, Value)>,
     set_into: Option<Tagged<String>>,
     get: Option<Tagged<String>>,
     clear: Tagged<bool>,
@@ -90,11 +91,12 @@ pub fn config(
                 .ok_or_else(|| ShellError::labeled_error("Missing key in config", "key", v.tag()))?;
 
             match value {
-                Tagged {
-                    item: Value::Table(list),
+                Value {
+                    value: UntaggedValue::Table(list),
                     ..
                 } => {
                     for l in list {
+                        let value = l.clone();
                         yield ReturnSuccess::value(l.clone());
                     }
                 }
@@ -106,10 +108,10 @@ pub fn config(
 
             config::write(&result, &configuration)?;
 
-            yield ReturnSuccess::value(Value::Row(result.into()).tagged(value.tag()));
+            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(&value.tag));
         }
         else if let Some(v) = set_into {
-            let rows: Vec<Tagged<Value>> = input.values.collect().await;
+            let rows: Vec<Value> = input.values.collect().await;
             let key = v.to_string();
 
             if rows.len() == 0 {
@@ -122,16 +124,16 @@ pub fn config(
 
                 config::write(&result, &configuration)?;
 
-                yield ReturnSuccess::value(Value::Row(result.into()).tagged(name));
+                yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
             } else {
                 // Take in the pipeline as a table
-                let value = Value::Table(rows).tagged(name.clone());
+                let value = UntaggedValue::Table(rows).into_value(name.clone());
 
                 result.insert(key.to_string(), value.clone());
 
                 config::write(&result, &configuration)?;
 
-                yield ReturnSuccess::value(Value::Row(result.into()).tagged(name));
+                yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
             }
         }
         else if let Tagged { item: true, tag } = clear {
@@ -139,14 +141,14 @@ pub fn config(
 
             config::write(&result, &configuration)?;
 
-            yield ReturnSuccess::value(Value::Row(result.into()).tagged(tag));
+            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(tag));
 
             return;
         }
         else if let Tagged { item: true, tag } = path {
             let path = config::default_path_for(&configuration)?;
 
-            yield ReturnSuccess::value(Value::Primitive(Primitive::Path(path)).tagged(tag));
+            yield ReturnSuccess::value(UntaggedValue::Primitive(Primitive::Path(path)).into_value(tag));
         }
         else if let Some(v) = remove {
             let key = v.to_string();
@@ -162,10 +164,10 @@ pub fn config(
                 ));
             }
 
-            yield ReturnSuccess::value(Value::Row(result.into()).tagged(v.tag()));
+            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(v.tag()));
         }
         else {
-            yield ReturnSuccess::value(Value::Row(result.into()).tagged(name));
+            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
         }
     };
 

src/commands/count.rs

@@ -37,9 +37,9 @@ pub fn count(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let rows: Vec<Tagged<Value>> = input.values.collect().await;
+        let rows: Vec<Value> = input.values.collect().await;
 
-        yield ReturnSuccess::value(Value::int(rows.len()).tagged(name))
+        yield ReturnSuccess::value(UntaggedValue::int(rows.len()).into_value(name))
     };
 
     Ok(stream.to_output_stream())

src/commands/cp.rs

@@ -3,6 +3,7 @@ use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::{CommandRegistry, Signature};
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct Cpy;
@@ -35,7 +36,7 @@ impl PerItemCommand for Cpy {
         call_info: &CallInfo,
         _registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         call_info.process(&raw_args.shell_manager, cp)?.run()
     }

src/commands/date.rs

@@ -35,26 +35,44 @@ impl WholeStreamCommand for Date {
     }
 }
 
-pub fn date_to_value<T: TimeZone>(dt: DateTime<T>, tag: Tag) -> Tagged<Value>
+pub fn date_to_value<T: TimeZone>(dt: DateTime<T>, tag: Tag) -> Value
 where
     T::Offset: Display,
 {
     let mut indexmap = IndexMap::new();
 
-    indexmap.insert("year".to_string(), Value::int(dt.year()).tagged(&tag));
-    indexmap.insert("month".to_string(), Value::int(dt.month()).tagged(&tag));
-    indexmap.insert("day".to_string(), Value::int(dt.day()).tagged(&tag));
-    indexmap.insert("hour".to_string(), Value::int(dt.hour()).tagged(&tag));
-    indexmap.insert("minute".to_string(), Value::int(dt.minute()).tagged(&tag));
-    indexmap.insert("second".to_string(), Value::int(dt.second()).tagged(&tag));
+    indexmap.insert(
+        "year".to_string(),
+        UntaggedValue::int(dt.year()).into_value(&tag),
+    );
+    indexmap.insert(
+        "month".to_string(),
+        UntaggedValue::int(dt.month()).into_value(&tag),
+    );
+    indexmap.insert(
+        "day".to_string(),
+        UntaggedValue::int(dt.day()).into_value(&tag),
+    );
+    indexmap.insert(
+        "hour".to_string(),
+        UntaggedValue::int(dt.hour()).into_value(&tag),
+    );
+    indexmap.insert(
+        "minute".to_string(),
+        UntaggedValue::int(dt.minute()).into_value(&tag),
+    );
+    indexmap.insert(
+        "second".to_string(),
+        UntaggedValue::int(dt.second()).into_value(&tag),
+    );
 
     let tz = dt.offset();
     indexmap.insert(
         "timezone".to_string(),
-        Value::string(format!("{}", tz)).tagged(&tag),
+        UntaggedValue::string(format!("{}", tz)).into_value(&tag),
     );
 
-    Value::Row(Dictionary::from(indexmap)).tagged(&tag)
+    UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag)
 }
 
 pub fn date(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {

src/commands/debug.rs

@@ -34,6 +34,8 @@ fn debug_value(
 ) -> Result<impl ToOutputStream, ShellError> {
     Ok(input
         .values
-        .map(|v| ReturnSuccess::value(Value::string(format!("{:?}", v)).tagged_unknown()))
+        .map(|v| {
+            ReturnSuccess::value(UntaggedValue::string(format!("{:?}", v)).into_untagged_value())
+        })
         .to_output_stream())
 }

src/commands/default.rs

@@ -2,11 +2,12 @@ use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::parser::CommandRegistry;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 struct DefaultArgs {
     column: Tagged<String>,
-    value: Tagged<Value>,
+    value: Value,
 }
 
 pub struct Default;
@@ -49,15 +50,15 @@ fn default(
             let mut result = VecDeque::new();
 
             let should_add = match item {
-                Tagged {
-                    item: Value::Row(ref r),
+                Value {
+                    value: UntaggedValue::Row(ref r),
                     ..
                 } => r.get_data(&column.item).borrow().is_none(),
                 _ => false,
             };
 
             if should_add {
-                match item.insert_data_at_path(&column.item, value.item.clone()) {
+                match item.insert_data_at_path(&column.item, value.clone()) {
                     Some(new_value) => result.push_back(ReturnSuccess::value(new_value)),
                     None => result.push_back(ReturnSuccess::value(item)),
                 }

src/commands/echo.rs

@@ -24,7 +24,7 @@ impl PerItemCommand for Echo {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         run(call_info, registry, raw_args)
     }
@@ -42,16 +42,16 @@ fn run(
             match i.as_string() {
                 Ok(s) => {
                     output.push(Ok(ReturnSuccess::Value(
-                        Value::string(s).tagged(i.tag.clone()),
+                        UntaggedValue::string(s).into_value(i.tag.clone()),
                     )));
                 }
                 _ => match i {
-                    Tagged {
-                        item: Value::Table(table),
+                    Value {
+                        value: UntaggedValue::Table(table),
                         ..
                     } => {
-                        for item in table {
-                            output.push(Ok(ReturnSuccess::Value(item.clone())));
+                        for value in table {
+                            output.push(Ok(ReturnSuccess::Value(value.clone())));
                         }
                     }
                     _ => {

src/commands/enter.rs

@@ -30,13 +30,13 @@ impl PerItemCommand for Enter {
         call_info: &CallInfo,
         registry: &registry::CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         let registry = registry.clone();
         let raw_args = raw_args.clone();
         match call_info.args.expect_nth(0)? {
-            Tagged {
-                item: Value::Primitive(Primitive::Path(location)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Path(location)),
                 tag,
                 ..
             } => {
@@ -51,12 +51,12 @@ impl PerItemCommand for Enter {
 
                     if registry.has(command) {
                         Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
-                            Value::string(command).tagged(Tag::unknown()),
+                            UntaggedValue::string(command).into_value(Tag::unknown()),
                         )))]
                         .into())
                     } else {
                         Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
-                            Value::nothing().tagged(Tag::unknown()),
+                            UntaggedValue::nothing().into_value(Tag::unknown()),
                         )))]
                         .into())
                     }
@@ -80,8 +80,8 @@ impl PerItemCommand for Enter {
                             ).await?;
 
                         match contents {
-                            Value::Primitive(Primitive::String(_)) => {
-                                let tagged_contents = contents.tagged(&contents_tag);
+                            UntaggedValue::Primitive(Primitive::String(_)) => {
+                                let tagged_contents = contents.into_value(&contents_tag);
 
                                 if let Some(extension) = file_extension {
                                     let command_name = format!("from-{}", extension);
@@ -97,6 +97,7 @@ impl PerItemCommand for Enter {
                                                     head: raw_args.call_info.args.head,
                                                     positional: None,
                                                     named: None,
+                                                    span: Span::unknown()
                                                 },
                                                 source: raw_args.call_info.source,
                                                 name_tag: raw_args.call_info.name_tag,
@@ -110,13 +111,13 @@ impl PerItemCommand for Enter {
                                             result.drain_vec().await;
                                         for res in result_vec {
                                             match res {
-                                                Ok(ReturnSuccess::Value(Tagged {
-                                                    item,
+                                                Ok(ReturnSuccess::Value(Value {
+                                                    value,
                                                     ..
                                                 })) => {
                                                     yield Ok(ReturnSuccess::Action(CommandAction::EnterValueShell(
-                                                        Tagged {
-                                                            item,
+                                                        Value {
+                                                            value,
                                                             tag: contents_tag.clone(),
                                                         })));
                                                 }
@@ -131,7 +132,7 @@ impl PerItemCommand for Enter {
                                 }
                             }
                             _ => {
-                                let tagged_contents = contents.tagged(contents_tag);
+                                let tagged_contents = contents.into_value(contents_tag);
 
                                 yield Ok(ReturnSuccess::Action(CommandAction::EnterValueShell(tagged_contents)));
                             }

src/commands/env.rs

@@ -33,34 +33,49 @@ impl WholeStreamCommand for Env {
     }
 }
 
-pub fn get_environment(tag: Tag) -> Result<Tagged<Value>, Box<dyn std::error::Error>> {
+pub fn get_environment(tag: Tag) -> Result<Value, Box<dyn std::error::Error>> {
     let mut indexmap = IndexMap::new();
 
     let path = std::env::current_dir()?;
-    indexmap.insert("cwd".to_string(), Value::path(path).tagged(&tag));
+    indexmap.insert(
+        "cwd".to_string(),
+        UntaggedValue::path(path).into_value(&tag),
+    );
 
     if let Some(home) = dirs::home_dir() {
-        indexmap.insert("home".to_string(), Value::path(home).tagged(&tag));
+        indexmap.insert(
+            "home".to_string(),
+            UntaggedValue::path(home).into_value(&tag),
+        );
     }
 
     let config = config::default_path()?;
-    indexmap.insert("config".to_string(), Value::path(config).tagged(&tag));
+    indexmap.insert(
+        "config".to_string(),
+        UntaggedValue::path(config).into_value(&tag),
+    );
 
     let history = History::path();
-    indexmap.insert("history".to_string(), Value::path(history).tagged(&tag));
+    indexmap.insert(
+        "history".to_string(),
+        UntaggedValue::path(history).into_value(&tag),
+    );
 
     let temp = std::env::temp_dir();
-    indexmap.insert("temp".to_string(), Value::path(temp).tagged(&tag));
+    indexmap.insert(
+        "temp".to_string(),
+        UntaggedValue::path(temp).into_value(&tag),
+    );
 
     let mut dict = TaggedDictBuilder::new(&tag);
     for v in std::env::vars() {
-        dict.insert(v.0, Value::string(v.1));
+        dict.insert_untagged(v.0, UntaggedValue::string(v.1));
     }
     if !dict.is_empty() {
-        indexmap.insert("vars".to_string(), dict.into_tagged_value());
+        indexmap.insert("vars".to_string(), dict.into_value());
     }
 
-    Ok(Value::Row(Dictionary::from(indexmap)).tagged(&tag))
+    Ok(UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag))
 }
 
 pub fn env(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {

src/commands/evaluate_by.rs

@@ -1,6 +1,8 @@
 use crate::commands::WholeStreamCommand;
 use crate::parser::hir::SyntaxShape;
 use crate::prelude::*;
+use nu_source::{SpannedItem, Tagged};
+
 pub struct EvaluateBy;
 
 #[derive(Deserialize)]
@@ -39,7 +41,7 @@ pub fn evaluate_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
 
         if values.is_empty() {
@@ -66,30 +68,18 @@ pub fn evaluate_by(
     Ok(stream.to_output_stream())
 }
 
-fn fetch(
-    key: Option<String>,
-) -> Box<dyn Fn(Tagged<Value>, Tag) -> Option<Tagged<Value>> + 'static> {
-    Box::new(move |value: Tagged<Value>, tag| match key {
-        Some(ref key_given) => {
-            if let Some(Tagged {
-                item,
-                tag: Tag { span, .. },
-            }) = value.get_data_by_key(key_given[..].spanned(tag.span))
-            {
-                Some(item.clone().tagged(tag))
-            } else {
-                None
-            }
-        }
-        None => Some(Value::int(1).tagged(tag)),
+fn fetch(key: Option<String>) -> Box<dyn Fn(Value, Tag) -> Option<Value> + 'static> {
+    Box::new(move |value: Value, tag| match &key {
+        Some(key_given) => value.get_data_by_key(key_given[..].spanned(tag.span)),
+        None => Some(UntaggedValue::int(1).into_value(tag)),
     })
 }
 
 pub fn evaluate(
-    values: &Tagged<Value>,
+    values: &Value,
     evaluator: Option<String>,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let tag = tag.into();
 
     let evaluate_with = match evaluator {
@@ -97,44 +87,44 @@ pub fn evaluate(
         None => fetch(None),
     };
 
-    let results: Tagged<Value> = match values {
-        Tagged {
-            item: Value::Table(datasets),
+    let results: Value = match values {
+        Value {
+            value: UntaggedValue::Table(datasets),
             ..
         } => {
             let datasets: Vec<_> = datasets
                 .into_iter()
                 .map(|subsets| match subsets {
-                    Tagged {
-                        item: Value::Table(subsets),
+                    Value {
+                        value: UntaggedValue::Table(subsets),
                         ..
                     } => {
                         let subsets: Vec<_> = subsets
                             .clone()
                             .into_iter()
                             .map(|data| match data {
-                                Tagged {
-                                    item: Value::Table(data),
+                                Value {
+                                    value: UntaggedValue::Table(data),
                                     ..
                                 } => {
                                     let data: Vec<_> = data
                                         .into_iter()
                                         .map(|x| evaluate_with(x.clone(), tag.clone()).unwrap())
                                         .collect();
-                                    Value::Table(data).tagged(&tag)
+                                    UntaggedValue::Table(data).into_value(&tag)
                                 }
-                                _ => Value::Table(vec![]).tagged(&tag),
+                                _ => UntaggedValue::Table(vec![]).into_value(&tag),
                             })
                             .collect();
-                        Value::Table(subsets).tagged(&tag)
+                        UntaggedValue::Table(subsets).into_value(&tag)
                     }
-                    _ => Value::Table(vec![]).tagged(&tag),
+                    _ => UntaggedValue::Table(vec![]).into_value(&tag),
                 })
                 .collect();
 
-            Value::Table(datasets.clone()).tagged(&tag)
+            UntaggedValue::Table(datasets.clone()).into_value(&tag)
         }
-        _ => Value::Table(vec![]).tagged(&tag),
+        _ => UntaggedValue::Table(vec![]).into_value(&tag),
     };
 
     Ok(results)
@@ -146,28 +136,28 @@ mod tests {
     use crate::commands::evaluate_by::{evaluate, fetch};
     use crate::commands::group_by::group;
     use crate::commands::t_sort_by::t_sort;
-    use crate::data::meta::*;
     use crate::prelude::*;
     use crate::Value;
     use indexmap::IndexMap;
+    use nu_source::TaggedItem;
 
-    fn int(s: impl Into<BigInt>) -> Tagged<Value> {
-        Value::int(s).tagged_unknown()
+    fn int(s: impl Into<BigInt>) -> Value {
+        UntaggedValue::int(s).into_untagged_value()
     }
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn nu_releases_sorted_by_date() -> Tagged<Value> {
+    fn nu_releases_sorted_by_date() -> Value {
         let key = String::from("date");
 
         t_sort(
@@ -179,12 +169,12 @@ mod tests {
         .unwrap()
     }
 
-    fn nu_releases_grouped_by_date() -> Tagged<Value> {
+    fn nu_releases_grouped_by_date() -> Value {
         let key = String::from("date").tagged_unknown();
         group(&key, nu_releases_commiters(), Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},
@@ -232,7 +222,7 @@ mod tests {
 
         assert_eq!(
             evaluator(subject, Tag::unknown()),
-            Some(Value::int(1).tagged_unknown())
+            Some(UntaggedValue::int(1).into_untagged_value())
         );
     }
 

src/commands/fetch.rs

@@ -1,15 +1,15 @@
 use crate::commands::UnevaluatedCallInfo;
-use crate::context::AnchorLocation;
-use crate::data::meta::Span;
-use crate::data::Value;
+use crate::data::base::Value;
 use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::Signature;
 use crate::prelude::*;
 use mime::Mime;
+use nu_source::{AnchorLocation, Span};
 use std::path::PathBuf;
 use std::str::FromStr;
 use surf::mime;
+
 pub struct Fetch;
 
 impl PerItemCommand for Fetch {
@@ -36,7 +36,7 @@ impl PerItemCommand for Fetch {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         run(call_info, registry, raw_args)
     }
@@ -81,7 +81,7 @@ fn run(
             file_extension.or(path_str.split('.').last().map(String::from))
         };
 
-        let tagged_contents = contents.tagged(&contents_tag);
+        let tagged_contents = contents.retag(&contents_tag);
 
         if let Some(extension) = file_extension {
             let command_name = format!("from-{}", extension);
@@ -94,7 +94,8 @@ fn run(
                         args: crate::parser::hir::Call {
                             head: raw_args.call_info.args.head,
                             positional: None,
-                            named: None
+                            named: None,
+                            span: Span::unknown()
                         },
                         source: raw_args.call_info.source,
                         name_tag: raw_args.call_info.name_tag,
@@ -104,13 +105,13 @@ fn run(
                 let result_vec: Vec<Result<ReturnSuccess, ShellError>> = result.drain_vec().await;
                 for res in result_vec {
                     match res {
-                        Ok(ReturnSuccess::Value(Tagged { item: Value::Table(list), ..})) => {
+                        Ok(ReturnSuccess::Value(Value { value: UntaggedValue::Table(list), ..})) => {
                             for l in list {
                                 yield Ok(ReturnSuccess::Value(l));
                             }
                         }
-                        Ok(ReturnSuccess::Value(Tagged { item, .. })) => {
-                            yield Ok(ReturnSuccess::Value(Tagged { item, tag: contents_tag.clone() }));
+                        Ok(ReturnSuccess::Value(Value { value, .. })) => {
+                            yield Ok(ReturnSuccess::Value(value.into_value(contents_tag.clone())));
                         }
                         x => yield x,
                     }
@@ -126,7 +127,10 @@ fn run(
     Ok(stream.to_output_stream())
 }
 
-pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value, Tag), ShellError> {
+pub async fn fetch(
+    location: &str,
+    span: Span,
+) -> Result<(Option<String>, UntaggedValue, Tag), ShellError> {
     if let Err(_) = url::Url::parse(location) {
         return Err(ShellError::labeled_error(
             "Incomplete or incorrect url",
@@ -143,7 +147,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                 match (content_type.type_(), content_type.subtype()) {
                     (mime::APPLICATION, mime::XML) => Ok((
                         Some("xml".to_string()),
-                        Value::string(r.body_string().await.map_err(|_| {
+                        UntaggedValue::string(r.body_string().await.map_err(|_| {
                             ShellError::labeled_error(
                                 "Could not load text from remote url",
                                 "could not load",
@@ -157,7 +161,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                     )),
                     (mime::APPLICATION, mime::JSON) => Ok((
                         Some("json".to_string()),
-                        Value::string(r.body_string().await.map_err(|_| {
+                        UntaggedValue::string(r.body_string().await.map_err(|_| {
                             ShellError::labeled_error(
                                 "Could not load text from remote url",
                                 "could not load",
@@ -179,7 +183,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                         })?;
                         Ok((
                             None,
-                            Value::binary(buf),
+                            UntaggedValue::binary(buf),
                             Tag {
                                 span,
                                 anchor: Some(AnchorLocation::Url(location.to_string())),
@@ -188,7 +192,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                     }
                     (mime::IMAGE, mime::SVG) => Ok((
                         Some("svg".to_string()),
-                        Value::string(r.body_string().await.map_err(|_| {
+                        UntaggedValue::string(r.body_string().await.map_err(|_| {
                             ShellError::labeled_error(
                                 "Could not load svg from remote url",
                                 "could not load",
@@ -210,7 +214,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                         })?;
                         Ok((
                             Some(image_ty.to_string()),
-                            Value::binary(buf),
+                            UntaggedValue::binary(buf),
                             Tag {
                                 span,
                                 anchor: Some(AnchorLocation::Url(location.to_string())),
@@ -219,7 +223,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                     }
                     (mime::TEXT, mime::HTML) => Ok((
                         Some("html".to_string()),
-                        Value::string(r.body_string().await.map_err(|_| {
+                        UntaggedValue::string(r.body_string().await.map_err(|_| {
                             ShellError::labeled_error(
                                 "Could not load text from remote url",
                                 "could not load",
@@ -245,7 +249,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
 
                         Ok((
                             path_extension,
-                            Value::string(r.body_string().await.map_err(|_| {
+                            UntaggedValue::string(r.body_string().await.map_err(|_| {
                                 ShellError::labeled_error(
                                     "Could not load text from remote url",
                                     "could not load",
@@ -260,7 +264,10 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
                     }
                     (ty, sub_ty) => Ok((
                         None,
-                        Value::string(format!("Not yet supported MIME type: {} {}", ty, sub_ty)),
+                        UntaggedValue::string(format!(
+                            "Not yet supported MIME type: {} {}",
+                            ty, sub_ty
+                        )),
                         Tag {
                             span,
                             anchor: Some(AnchorLocation::Url(location.to_string())),
@@ -270,7 +277,7 @@ pub async fn fetch(location: &str, span: Span) -> Result<(Option<String>, Value,
             }
             None => Ok((
                 None,
-                Value::string(format!("No content type found")),
+                UntaggedValue::string(format!("No content type found")),
                 Tag {
                     span,
                     anchor: Some(AnchorLocation::Url(location.to_string())),

src/commands/first.rs

@@ -2,6 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::parser::CommandRegistry;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct First;
 

src/commands/from_bson.rs

@@ -1,8 +1,9 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, TaggedDictBuilder, Value};
+use crate::data::TaggedDictBuilder;
 use crate::errors::ExpectedRange;
 use crate::prelude::*;
 use bson::{decode_document, spec::BinarySubtype, Bson};
+use nu_source::SpannedItem;
 use std::str::FromStr;
 
 pub struct FromBSON;
@@ -29,7 +30,7 @@ impl WholeStreamCommand for FromBSON {
     }
 }
 
-fn bson_array(input: &Vec<Bson>, tag: Tag) -> Result<Vec<Tagged<Value>>, ShellError> {
+fn bson_array(input: &Vec<Bson>, tag: Tag) -> Result<Vec<Value>, ShellError> {
     let mut out = vec![];
 
     for value in input {
@@ -39,109 +40,114 @@ fn bson_array(input: &Vec<Bson>, tag: Tag) -> Result<Vec<Tagged<Value>>, ShellEr
     Ok(out)
 }
 
-fn convert_bson_value_to_nu_value(
-    v: &Bson,
-    tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+fn convert_bson_value_to_nu_value(v: &Bson, tag: impl Into<Tag>) -> Result<Value, ShellError> {
     let tag = tag.into();
+    let span = tag.span;
 
     Ok(match v {
-        Bson::FloatingPoint(n) => Value::Primitive(Primitive::from(*n)).tagged(&tag),
-        Bson::String(s) => Value::Primitive(Primitive::String(String::from(s))).tagged(&tag),
-        Bson::Array(a) => Value::Table(bson_array(a, tag.clone())?).tagged(&tag),
+        Bson::FloatingPoint(n) => UntaggedValue::Primitive(Primitive::from(*n)).into_value(&tag),
+        Bson::String(s) => {
+            UntaggedValue::Primitive(Primitive::String(String::from(s))).into_value(&tag)
+        }
+        Bson::Array(a) => UntaggedValue::Table(bson_array(a, tag.clone())?).into_value(&tag),
         Bson::Document(doc) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
             for (k, v) in doc.iter() {
-                collected.insert_tagged(k.clone(), convert_bson_value_to_nu_value(v, &tag)?);
+                collected.insert_value(k.clone(), convert_bson_value_to_nu_value(v, &tag)?);
             }
 
-            collected.into_tagged_value()
+            collected.into_value()
         }
-        Bson::Boolean(b) => Value::Primitive(Primitive::Boolean(*b)).tagged(&tag),
-        Bson::Null => Value::Primitive(Primitive::Nothing).tagged(&tag),
+        Bson::Boolean(b) => UntaggedValue::Primitive(Primitive::Boolean(*b)).into_value(&tag),
+        Bson::Null => UntaggedValue::Primitive(Primitive::Nothing).into_value(&tag),
         Bson::RegExp(r, opts) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$regex".to_string(),
-                Value::Primitive(Primitive::String(String::from(r))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(r))).into_value(&tag),
             );
-            collected.insert_tagged(
+            collected.insert_value(
                 "$options".to_string(),
-                Value::Primitive(Primitive::String(String::from(opts))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(opts))).into_value(&tag),
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
-        Bson::I32(n) => Value::number(n).tagged(&tag),
-        Bson::I64(n) => Value::number(n).tagged(&tag),
+        Bson::I32(n) => UntaggedValue::number(n).into_value(&tag),
+        Bson::I64(n) => UntaggedValue::number(n).into_value(&tag),
         Bson::Decimal128(n) => {
             // TODO: this really isn't great, and we should update this to do a higher
             // fidelity translation
             let decimal = BigDecimal::from_str(&format!("{}", n)).map_err(|_| {
                 ShellError::range_error(
                     ExpectedRange::BigDecimal,
-                    &n.tagged(&tag),
+                    &n.spanned(span),
                     format!("converting BSON Decimal128 to BigDecimal"),
                 )
             })?;
-            Value::Primitive(Primitive::Decimal(decimal)).tagged(&tag)
+            UntaggedValue::Primitive(Primitive::Decimal(decimal)).into_value(&tag)
         }
         Bson::JavaScriptCode(js) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$javascript".to_string(),
-                Value::Primitive(Primitive::String(String::from(js))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(js))).into_value(&tag),
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
         Bson::JavaScriptCodeWithScope(js, doc) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$javascript".to_string(),
-                Value::Primitive(Primitive::String(String::from(js))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(js))).into_value(&tag),
             );
-            collected.insert_tagged(
+            collected.insert_value(
                 "$scope".to_string(),
                 convert_bson_value_to_nu_value(&Bson::Document(doc.to_owned()), tag.clone())?,
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
         Bson::TimeStamp(ts) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged("$timestamp".to_string(), Value::number(ts).tagged(&tag));
-            collected.into_tagged_value()
+            collected.insert_value(
+                "$timestamp".to_string(),
+                UntaggedValue::number(ts).into_value(&tag),
+            );
+            collected.into_value()
         }
         Bson::Binary(bst, bytes) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$binary_subtype".to_string(),
                 match bst {
-                    BinarySubtype::UserDefined(u) => Value::number(u),
-                    _ => Value::Primitive(Primitive::String(binary_subtype_to_string(*bst))),
+                    BinarySubtype::UserDefined(u) => UntaggedValue::number(u),
+                    _ => {
+                        UntaggedValue::Primitive(Primitive::String(binary_subtype_to_string(*bst)))
+                    }
                 }
-                .tagged(&tag),
+                .into_value(&tag),
             );
-            collected.insert_tagged(
+            collected.insert_value(
                 "$binary".to_string(),
-                Value::Primitive(Primitive::Binary(bytes.to_owned())).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::Binary(bytes.to_owned())).into_value(&tag),
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
         Bson::ObjectId(obj_id) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$object_id".to_string(),
-                Value::Primitive(Primitive::String(obj_id.to_hex())).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(obj_id.to_hex())).into_value(&tag),
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
-        Bson::UtcDatetime(dt) => Value::Primitive(Primitive::Date(*dt)).tagged(&tag),
+        Bson::UtcDatetime(dt) => UntaggedValue::Primitive(Primitive::Date(*dt)).into_value(&tag),
         Bson::Symbol(s) => {
             let mut collected = TaggedDictBuilder::new(tag.clone());
-            collected.insert_tagged(
+            collected.insert_value(
                 "$symbol".to_string(),
-                Value::Primitive(Primitive::String(String::from(s))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(s))).into_value(&tag),
             );
-            collected.into_tagged_value()
+            collected.into_value()
         }
     })
 }
@@ -183,10 +189,7 @@ impl std::io::Read for BytesReader {
     }
 }
 
-pub fn from_bson_bytes_to_value(
-    bytes: Vec<u8>,
-    tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+pub fn from_bson_bytes_to_value(bytes: Vec<u8>, tag: impl Into<Tag>) -> Result<Value, ShellError> {
     let mut docs = Vec::new();
     let mut b_reader = BytesReader::new(bytes);
     while let Ok(v) = decode_document(&mut b_reader) {
@@ -202,12 +205,12 @@ fn from_bson(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStre
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         for value in values {
-            let value_tag = value.tag();
-            match value.item {
-                Value::Primitive(Primitive::Binary(vb)) =>
+            let value_tag = &value.tag;
+            match value.value {
+                UntaggedValue::Primitive(Primitive::Binary(vb)) =>
                     match from_bson_bytes_to_value(vb, tag.clone()) {
                         Ok(x) => yield ReturnSuccess::value(x),
                         Err(_) => {

src/commands/from_csv.rs

@@ -8,7 +8,7 @@ pub struct FromCSV;
 #[derive(Deserialize)]
 pub struct FromCSVArgs {
     headerless: bool,
-    separator: Option<Tagged<Value>>,
+    separator: Option<Value>,
 }
 
 impl WholeStreamCommand for FromCSV {
@@ -47,8 +47,8 @@ fn from_csv(
     runnable_context: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let sep = match separator {
-        Some(Tagged {
-            item: Value::Primitive(Primitive::String(s)),
+        Some(Value {
+            value: UntaggedValue::Primitive(Primitive::String(s)),
             tag,
             ..
         }) => {

src/commands/from_delimited_data.rs

@@ -7,7 +7,7 @@ fn from_delimited_string_to_value(
     headerless: bool,
     separator: char,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, csv::Error> {
+) -> Result<Value, csv::Error> {
     let mut reader = ReaderBuilder::new()
         .has_headers(!headerless)
         .delimiter(separator as u8)
@@ -26,15 +26,15 @@ fn from_delimited_string_to_value(
     for row in reader.records() {
         let mut tagged_row = TaggedDictBuilder::new(&tag);
         for (value, header) in row?.iter().zip(headers.iter()) {
-            tagged_row.insert_tagged(
+            tagged_row.insert_value(
                 header,
-                Value::Primitive(Primitive::String(String::from(value))).tagged(&tag),
+                UntaggedValue::Primitive(Primitive::String(String::from(value))).into_value(&tag),
             )
         }
-        rows.push(tagged_row.into_tagged_value());
+        rows.push(tagged_row.into_value());
     }
 
-    Ok(Value::Table(rows).tagged(&tag))
+    Ok(UntaggedValue::Table(rows).into_value(&tag))
 }
 
 pub fn from_delimited_data(
@@ -46,16 +46,16 @@ pub fn from_delimited_data(
     let name_tag = name;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
+            let value_tag = &value.tag;
             latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
@@ -72,7 +72,7 @@ pub fn from_delimited_data(
 
         match from_delimited_string_to_value(concat_string, headerless, sep, name_tag.clone()) {
             Ok(x) => match x {
-                Tagged { item: Value::Table(list), .. } => {
+                Value { value: UntaggedValue::Table(list), .. } => {
                     for l in list {
                         yield ReturnSuccess::value(l);
                     }

src/commands/from_ini.rs

@@ -27,40 +27,37 @@ impl WholeStreamCommand for FromINI {
     }
 }
 
-fn convert_ini_second_to_nu_value(
-    v: &HashMap<String, String>,
-    tag: impl Into<Tag>,
-) -> Tagged<Value> {
+fn convert_ini_second_to_nu_value(v: &HashMap<String, String>, tag: impl Into<Tag>) -> Value {
     let mut second = TaggedDictBuilder::new(tag);
 
     for (key, value) in v.into_iter() {
-        second.insert(key.clone(), Primitive::String(value.clone()));
+        second.insert_untagged(key.clone(), Primitive::String(value.clone()));
     }
 
-    second.into_tagged_value()
+    second.into_value()
 }
 
 fn convert_ini_top_to_nu_value(
     v: &HashMap<String, HashMap<String, String>>,
     tag: impl Into<Tag>,
-) -> Tagged<Value> {
+) -> Value {
     let tag = tag.into();
     let mut top_level = TaggedDictBuilder::new(tag.clone());
 
     for (key, value) in v.iter() {
-        top_level.insert_tagged(
+        top_level.insert_value(
             key.clone(),
             convert_ini_second_to_nu_value(value, tag.clone()),
         );
     }
 
-    top_level.into_tagged_value()
+    top_level.into_value()
 }
 
 pub fn from_ini_string_to_value(
     s: String,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, serde_ini::de::Error> {
+) -> Result<Value, serde_ini::de::Error> {
     let v: HashMap<String, HashMap<String, String>> = serde_ini::from_str(&s)?;
     Ok(convert_ini_top_to_nu_value(&v, tag))
 }
@@ -68,28 +65,29 @@ pub fn from_ini_string_to_value(
 fn from_ini(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let span = tag.span;
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -97,7 +95,7 @@ fn from_ini(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
 
         match from_ini_string_to_value(concat_string, tag.clone()) {
             Ok(x) => match x {
-                Tagged { item: Value::Table(list), .. } => {
+                Value { value: UntaggedValue::Table(list), .. } => {
                     for l in list {
                         yield ReturnSuccess::value(l);
                     }

src/commands/from_json.rs

@@ -31,39 +31,36 @@ impl WholeStreamCommand for FromJSON {
     }
 }
 
-fn convert_json_value_to_nu_value(v: &serde_hjson::Value, tag: impl Into<Tag>) -> Tagged<Value> {
+fn convert_json_value_to_nu_value(v: &serde_hjson::Value, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     match v {
-        serde_hjson::Value::Null => Value::Primitive(Primitive::Nothing).tagged(&tag),
-        serde_hjson::Value::Bool(b) => Value::boolean(*b).tagged(&tag),
-        serde_hjson::Value::F64(n) => Value::number(n).tagged(&tag),
-        serde_hjson::Value::U64(n) => Value::number(n).tagged(&tag),
-        serde_hjson::Value::I64(n) => Value::number(n).tagged(&tag),
+        serde_hjson::Value::Null => UntaggedValue::Primitive(Primitive::Nothing).into_value(&tag),
+        serde_hjson::Value::Bool(b) => UntaggedValue::boolean(*b).into_value(&tag),
+        serde_hjson::Value::F64(n) => UntaggedValue::number(n).into_value(&tag),
+        serde_hjson::Value::U64(n) => UntaggedValue::number(n).into_value(&tag),
+        serde_hjson::Value::I64(n) => UntaggedValue::number(n).into_value(&tag),
         serde_hjson::Value::String(s) => {
-            Value::Primitive(Primitive::String(String::from(s))).tagged(&tag)
+            UntaggedValue::Primitive(Primitive::String(String::from(s))).into_value(&tag)
         }
-        serde_hjson::Value::Array(a) => Value::Table(
+        serde_hjson::Value::Array(a) => UntaggedValue::Table(
             a.iter()
                 .map(|x| convert_json_value_to_nu_value(x, &tag))
                 .collect(),
         )
-        .tagged(tag),
+        .into_value(tag),
         serde_hjson::Value::Object(o) => {
             let mut collected = TaggedDictBuilder::new(&tag);
             for (k, v) in o.iter() {
-                collected.insert_tagged(k.clone(), convert_json_value_to_nu_value(v, &tag));
+                collected.insert_value(k.clone(), convert_json_value_to_nu_value(v, &tag));
             }
 
-            collected.into_tagged_value()
+            collected.into_value()
         }
     }
 }
 
-pub fn from_json_string_to_value(
-    s: String,
-    tag: impl Into<Tag>,
-) -> serde_hjson::Result<Tagged<Value>> {
+pub fn from_json_string_to_value(s: String, tag: impl Into<Tag>) -> serde_hjson::Result<Value> {
     let v: serde_hjson::Value = serde_hjson::from_str(&s)?;
     Ok(convert_json_value_to_nu_value(&v, tag))
 }
@@ -72,28 +69,29 @@ fn from_json(
     FromJSONArgs { objects }: FromJSONArgs,
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
+    let name_span = name.span;
     let name_tag = name;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &name_tag,
+                    name_span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -125,7 +123,7 @@ fn from_json(
             match from_json_string_to_value(concat_string, name_tag.clone()) {
                 Ok(x) =>
                     match x {
-                        Tagged { item: Value::Table(list), .. } => {
+                        Value { value: UntaggedValue::Table(list), .. } => {
                             for l in list {
                                 yield ReturnSuccess::value(l);
                             }

src/commands/from_sqlite.rs

@@ -57,7 +57,7 @@ impl WholeStreamCommand for FromDB {
 pub fn convert_sqlite_file_to_nu_value(
     path: &Path,
     tag: impl Into<Tag> + Clone,
-) -> Result<Tagged<Value>, rusqlite::Error> {
+) -> Result<Value, rusqlite::Error> {
     let conn = Connection::open(path)?;
 
     let mut meta_out = Vec::new();
@@ -72,48 +72,54 @@ pub fn convert_sqlite_file_to_nu_value(
         while let Some(table_row) = table_rows.next()? {
             out.push(convert_sqlite_row_to_nu_value(table_row, tag.clone())?)
         }
-        meta_dict.insert_tagged(
+        meta_dict.insert_value(
             "table_name".to_string(),
-            Value::Primitive(Primitive::String(table_name)).tagged(tag.clone()),
+            UntaggedValue::Primitive(Primitive::String(table_name)).into_value(tag.clone()),
         );
-        meta_dict.insert_tagged("table_values", Value::Table(out).tagged(tag.clone()));
-        meta_out.push(meta_dict.into_tagged_value());
+        meta_dict.insert_value(
+            "table_values",
+            UntaggedValue::Table(out).into_value(tag.clone()),
+        );
+        meta_out.push(meta_dict.into_value());
     }
     let tag = tag.into();
-    Ok(Value::Table(meta_out).tagged(tag))
+    Ok(UntaggedValue::Table(meta_out).into_value(tag))
 }
 
 fn convert_sqlite_row_to_nu_value(
     row: &Row,
     tag: impl Into<Tag> + Clone,
-) -> Result<Tagged<Value>, rusqlite::Error> {
+) -> Result<Value, rusqlite::Error> {
     let mut collected = TaggedDictBuilder::new(tag.clone());
     for (i, c) in row.columns().iter().enumerate() {
-        collected.insert_tagged(
+        collected.insert_value(
             c.name().to_string(),
             convert_sqlite_value_to_nu_value(row.get_raw(i), tag.clone()),
         );
     }
-    return Ok(collected.into_tagged_value());
+    return Ok(collected.into_value());
 }
 
-fn convert_sqlite_value_to_nu_value(value: ValueRef, tag: impl Into<Tag> + Clone) -> Tagged<Value> {
+fn convert_sqlite_value_to_nu_value(value: ValueRef, tag: impl Into<Tag> + Clone) -> Value {
     match value {
-        ValueRef::Null => Value::Primitive(Primitive::String(String::from(""))).tagged(tag),
-        ValueRef::Integer(i) => Value::number(i).tagged(tag),
-        ValueRef::Real(f) => Value::number(f).tagged(tag),
+        ValueRef::Null => {
+            UntaggedValue::Primitive(Primitive::String(String::from(""))).into_value(tag)
+        }
+        ValueRef::Integer(i) => UntaggedValue::number(i).into_value(tag),
+        ValueRef::Real(f) => UntaggedValue::number(f).into_value(tag),
         t @ ValueRef::Text(_) => {
             // this unwrap is safe because we know the ValueRef is Text.
-            Value::Primitive(Primitive::String(t.as_str().unwrap().to_string())).tagged(tag)
+            UntaggedValue::Primitive(Primitive::String(t.as_str().unwrap().to_string()))
+                .into_value(tag)
         }
-        ValueRef::Blob(u) => Value::binary(u.to_owned()).tagged(tag),
+        ValueRef::Blob(u) => UntaggedValue::binary(u.to_owned()).into_value(tag),
     }
 }
 
 pub fn from_sqlite_bytes_to_value(
     mut bytes: Vec<u8>,
     tag: impl Into<Tag> + Clone,
-) -> Result<Tagged<Value>, std::io::Error> {
+) -> Result<Value, std::io::Error> {
     // FIXME: should probably write a sqlite virtual filesystem
     // that will allow us to use bytes as a file to avoid this
     // write out, but this will require C code. Might be
@@ -132,15 +138,15 @@ fn from_sqlite(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputSt
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         for value in values {
-            let value_tag = value.tag();
-            match value.item {
-                Value::Primitive(Primitive::Binary(vb)) =>
+            let value_tag = &value.tag;
+            match value.value {
+                UntaggedValue::Primitive(Primitive::Binary(vb)) =>
                     match from_sqlite_bytes_to_value(vb, tag.clone()) {
                         Ok(x) => match x {
-                            Tagged { item: Value::Table(list), .. } => {
+                            Value { value: UntaggedValue::Table(list), .. } => {
                                 for l in list {
                                     yield ReturnSuccess::value(l);
                                 }

src/commands/from_ssv.rs

@@ -1,6 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::data::{Primitive, TaggedDictBuilder, Value};
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct FromSSV;
 
@@ -223,23 +224,24 @@ fn from_ssv_string_to_value(
     aligned_columns: bool,
     split_at: usize,
     tag: impl Into<Tag>,
-) -> Option<Tagged<Value>> {
+) -> Option<Value> {
     let tag = tag.into();
     let rows = string_to_table(s, headerless, aligned_columns, split_at)?
         .iter()
         .map(|row| {
             let mut tagged_dict = TaggedDictBuilder::new(&tag);
             for (col, entry) in row {
-                tagged_dict.insert_tagged(
+                tagged_dict.insert_value(
                     col,
-                    Value::Primitive(Primitive::String(String::from(entry))).tagged(&tag),
+                    UntaggedValue::Primitive(Primitive::String(String::from(entry)))
+                        .into_value(&tag),
                 )
             }
-            tagged_dict.into_tagged_value()
+            tagged_dict.into_value()
         })
         .collect();
 
-    Some(Value::Table(rows).tagged(&tag))
+    Some(UntaggedValue::Table(rows).into_value(&tag))
 }
 
 fn from_ssv(
@@ -251,7 +253,7 @@ fn from_ssv(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
         let split_at = match minimum_spaces {
@@ -260,10 +262,10 @@ fn from_ssv(
         };
 
         for value in values {
-            let value_tag = value.tag();
+            let value_tag = value.tag.clone();
             latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary (
@@ -278,7 +280,7 @@ fn from_ssv(
 
         match from_ssv_string_to_value(&concat_string, headerless, aligned_columns, split_at, name.clone()) {
             Some(x) => match x {
-                Tagged { item: Value::Table(list), ..} => {
+                Value { value: UntaggedValue::Table(list), ..} => {
                     for l in list { yield ReturnSuccess::value(l) }
                 }
                 x => yield ReturnSuccess::value(x)

src/commands/from_toml.rs

@@ -26,39 +26,38 @@ impl WholeStreamCommand for FromTOML {
     }
 }
 
-pub fn convert_toml_value_to_nu_value(v: &toml::Value, tag: impl Into<Tag>) -> Tagged<Value> {
+pub fn convert_toml_value_to_nu_value(v: &toml::Value, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     match v {
-        toml::Value::Boolean(b) => Value::boolean(*b).tagged(tag),
-        toml::Value::Integer(n) => Value::number(n).tagged(tag),
-        toml::Value::Float(n) => Value::number(n).tagged(tag),
-        toml::Value::String(s) => Value::Primitive(Primitive::String(String::from(s))).tagged(tag),
-        toml::Value::Array(a) => Value::Table(
+        toml::Value::Boolean(b) => UntaggedValue::boolean(*b).into_value(tag),
+        toml::Value::Integer(n) => UntaggedValue::number(n).into_value(tag),
+        toml::Value::Float(n) => UntaggedValue::number(n).into_value(tag),
+        toml::Value::String(s) => {
+            UntaggedValue::Primitive(Primitive::String(String::from(s))).into_value(tag)
+        }
+        toml::Value::Array(a) => UntaggedValue::Table(
             a.iter()
                 .map(|x| convert_toml_value_to_nu_value(x, &tag))
                 .collect(),
         )
-        .tagged(tag),
+        .into_value(tag),
         toml::Value::Datetime(dt) => {
-            Value::Primitive(Primitive::String(dt.to_string())).tagged(tag)
+            UntaggedValue::Primitive(Primitive::String(dt.to_string())).into_value(tag)
         }
         toml::Value::Table(t) => {
             let mut collected = TaggedDictBuilder::new(&tag);
 
             for (k, v) in t.iter() {
-                collected.insert_tagged(k.clone(), convert_toml_value_to_nu_value(v, &tag));
+                collected.insert_value(k.clone(), convert_toml_value_to_nu_value(v, &tag));
             }
 
-            collected.into_tagged_value()
+            collected.into_value()
         }
     }
 }
 
-pub fn from_toml_string_to_value(
-    s: String,
-    tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, toml::de::Error> {
+pub fn from_toml_string_to_value(s: String, tag: impl Into<Tag>) -> Result<Value, toml::de::Error> {
     let v: toml::Value = s.parse::<toml::Value>()?;
     Ok(convert_toml_value_to_nu_value(&v, tag))
 }
@@ -69,28 +68,29 @@ pub fn from_toml(
 ) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let name_span = tag.span;
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+            match value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    name_span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -98,7 +98,7 @@ pub fn from_toml(
 
         match from_toml_string_to_value(concat_string, tag.clone()) {
             Ok(x) => match x {
-                Tagged { item: Value::Table(list), .. } => {
+                Value { value: UntaggedValue::Table(list), .. } => {
                     for l in list {
                         yield ReturnSuccess::value(l);
                     }

src/commands/from_url.rs

@@ -29,27 +29,28 @@ impl WholeStreamCommand for FromURL {
 fn from_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let name_span = tag.span;
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+            match value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    name_span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -62,10 +63,10 @@ fn from_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
                 let mut row = TaggedDictBuilder::new(tag);
 
                 for (k,v) in result {
-                    row.insert(k, Value::string(v));
+                    row.insert_untagged(k, UntaggedValue::string(v));
                 }
 
-                yield ReturnSuccess::value(row.into_tagged_value());
+                yield ReturnSuccess::value(row.into_value());
             }
             _ => {
                 if let Some(last_tag) = latest_tag {

src/commands/from_xlsx.rs

@@ -45,12 +45,14 @@ fn from_xlsx(
     let tag = runnable_context.name;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         for value in values {
-            let value_tag = value.tag();
-            match value.item {
-                Value::Primitive(Primitive::Binary(vb)) => {
+            let value_span = value.tag.span;
+            let value_tag = value.tag.clone();
+
+            match value.value {
+                UntaggedValue::Primitive(Primitive::Binary(vb)) => {
                     let mut buf: Cursor<Vec<u8>> = Cursor::new(vb);
                     let mut xls = Xlsx::<_>::new(buf).unwrap();
 
@@ -67,24 +69,24 @@ fn from_xlsx(
                             let mut row_output = TaggedDictBuilder::new(&tag);
                             for (i, cell) in row.iter().enumerate() {
                                 let value = match cell {
-                                    DataType::Empty => Value::nothing(),
-                                    DataType::String(s) => Value::string(s),
-                                    DataType::Float(f) => Value::decimal(*f),
-                                    DataType::Int(i) => Value::int(*i),
-                                    DataType::Bool(b) => Value::boolean(*b),
-                                    _ => Value::nothing(),
+                                    DataType::Empty => UntaggedValue::nothing(),
+                                    DataType::String(s) => UntaggedValue::string(s),
+                                    DataType::Float(f) => UntaggedValue::decimal(*f),
+                                    DataType::Int(i) => UntaggedValue::int(*i),
+                                    DataType::Bool(b) => UntaggedValue::boolean(*b),
+                                    _ => UntaggedValue::nothing(),
                                 };
 
-                                row_output.insert(&format!("Column{}", i), value);
+                                row_output.insert_untagged(&format!("Column{}", i), value);
                             }
 
-                            sheet_output.push(row_output.into_tagged_value().item);
+                            sheet_output.push_untagged(row_output.into_untagged_value());
                         }
 
-                        dict.insert(sheet_name, sheet_output.into_tagged_value().item);
+                        dict.insert_untagged(sheet_name, sheet_output.into_untagged_value());
                     }
 
-                    yield ReturnSuccess::value(dict.into_tagged_value());
+                    yield ReturnSuccess::value(dict.into_value());
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected binary data from pipeline",

src/commands/from_xml.rs

@@ -1,5 +1,6 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, TaggedDictBuilder, Value};
+use crate::data::base::{Primitive, UntaggedValue, Value};
+use crate::data::TaggedDictBuilder;
 use crate::prelude::*;
 
 pub struct FromXML;
@@ -26,7 +27,7 @@ impl WholeStreamCommand for FromXML {
     }
 }
 
-fn from_node_to_value<'a, 'd>(n: &roxmltree::Node<'a, 'd>, tag: impl Into<Tag>) -> Tagged<Value> {
+fn from_node_to_value<'a, 'd>(n: &roxmltree::Node<'a, 'd>, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     if n.is_element() {
@@ -37,11 +38,11 @@ fn from_node_to_value<'a, 'd>(n: &roxmltree::Node<'a, 'd>, tag: impl Into<Tag>)
             children_values.push(from_node_to_value(&c, &tag));
         }
 
-        let children_values: Vec<Tagged<Value>> = children_values
+        let children_values: Vec<Value> = children_values
             .into_iter()
             .filter(|x| match x {
-                Tagged {
-                    item: Value::Primitive(Primitive::String(f)),
+                Value {
+                    value: UntaggedValue::Primitive(Primitive::String(f)),
                     ..
                 } => {
                     if f.trim() == "" {
@@ -55,28 +56,25 @@ fn from_node_to_value<'a, 'd>(n: &roxmltree::Node<'a, 'd>, tag: impl Into<Tag>)
             .collect();
 
         let mut collected = TaggedDictBuilder::new(tag);
-        collected.insert(name.clone(), Value::Table(children_values));
+        collected.insert_untagged(name.clone(), UntaggedValue::Table(children_values));
 
-        collected.into_tagged_value()
+        collected.into_value()
     } else if n.is_comment() {
-        Value::string("<comment>").tagged(tag)
+        UntaggedValue::string("<comment>").into_value(tag)
     } else if n.is_pi() {
-        Value::string("<processing_instruction>").tagged(tag)
+        UntaggedValue::string("<processing_instruction>").into_value(tag)
     } else if n.is_text() {
-        Value::string(n.text().unwrap()).tagged(tag)
+        UntaggedValue::string(n.text().unwrap()).into_value(tag)
     } else {
-        Value::string("<unknown>").tagged(tag)
+        UntaggedValue::string("<unknown>").into_value(tag)
     }
 }
 
-fn from_document_to_value(d: &roxmltree::Document, tag: impl Into<Tag>) -> Tagged<Value> {
+fn from_document_to_value(d: &roxmltree::Document, tag: impl Into<Tag>) -> Value {
     from_node_to_value(&d.root_element(), tag)
 }
 
-pub fn from_xml_string_to_value(
-    s: String,
-    tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, roxmltree::Error> {
+pub fn from_xml_string_to_value(s: String, tag: impl Into<Tag>) -> Result<Value, roxmltree::Error> {
     let parsed = roxmltree::Document::parse(&s)?;
     Ok(from_document_to_value(&parsed, tag))
 }
@@ -84,28 +82,30 @@ pub fn from_xml_string_to_value(
 fn from_xml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let name_span = tag.span;
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+
+            match value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    name_span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -113,7 +113,7 @@ fn from_xml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
 
         match from_xml_string_to_value(concat_string, tag.clone()) {
             Ok(x) => match x {
-                Tagged { item: Value::Table(list), .. } => {
+                Value { value: UntaggedValue::Table(list), .. } => {
                     for l in list {
                         yield ReturnSuccess::value(l);
                     }
@@ -139,23 +139,23 @@ fn from_xml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
 mod tests {
 
     use crate::commands::from_xml;
-    use crate::data::meta::*;
-    use crate::Value;
+    use crate::data::base::{UntaggedValue, Value};
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn parse(xml: &str) -> Tagged<Value> {
+    fn parse(xml: &str) -> Value {
         from_xml::from_xml_string_to_value(xml.to_string(), Tag::unknown()).unwrap()
     }
 

src/commands/from_yaml.rs

@@ -50,47 +50,44 @@ impl WholeStreamCommand for FromYML {
     }
 }
 
-fn convert_yaml_value_to_nu_value(v: &serde_yaml::Value, tag: impl Into<Tag>) -> Tagged<Value> {
+fn convert_yaml_value_to_nu_value(v: &serde_yaml::Value, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     match v {
-        serde_yaml::Value::Bool(b) => Value::boolean(*b).tagged(tag),
+        serde_yaml::Value::Bool(b) => UntaggedValue::boolean(*b).into_value(tag),
         serde_yaml::Value::Number(n) if n.is_i64() => {
-            Value::number(n.as_i64().unwrap()).tagged(tag)
+            UntaggedValue::number(n.as_i64().unwrap()).into_value(tag)
         }
         serde_yaml::Value::Number(n) if n.is_f64() => {
-            Value::Primitive(Primitive::from(n.as_f64().unwrap())).tagged(tag)
+            UntaggedValue::Primitive(Primitive::from(n.as_f64().unwrap())).into_value(tag)
         }
-        serde_yaml::Value::String(s) => Value::string(s).tagged(tag),
-        serde_yaml::Value::Sequence(a) => Value::Table(
+        serde_yaml::Value::String(s) => UntaggedValue::string(s).into_value(tag),
+        serde_yaml::Value::Sequence(a) => UntaggedValue::Table(
             a.iter()
                 .map(|x| convert_yaml_value_to_nu_value(x, &tag))
                 .collect(),
         )
-        .tagged(tag),
+        .into_value(tag),
         serde_yaml::Value::Mapping(t) => {
             let mut collected = TaggedDictBuilder::new(&tag);
 
             for (k, v) in t.iter() {
                 match k {
                     serde_yaml::Value::String(k) => {
-                        collected.insert_tagged(k.clone(), convert_yaml_value_to_nu_value(v, &tag));
+                        collected.insert_value(k.clone(), convert_yaml_value_to_nu_value(v, &tag));
                     }
                     _ => unimplemented!("Unknown key type"),
                 }
             }
 
-            collected.into_tagged_value()
+            collected.into_value()
         }
-        serde_yaml::Value::Null => Value::Primitive(Primitive::Nothing).tagged(tag),
+        serde_yaml::Value::Null => UntaggedValue::Primitive(Primitive::Nothing).into_value(tag),
         x => unimplemented!("Unsupported yaml case: {:?}", x),
     }
 }
 
-pub fn from_yaml_string_to_value(
-    s: String,
-    tag: impl Into<Tag>,
-) -> serde_yaml::Result<Tagged<Value>> {
+pub fn from_yaml_string_to_value(s: String, tag: impl Into<Tag>) -> serde_yaml::Result<Value> {
     let v: serde_yaml::Value = serde_yaml::from_str(&s)?;
     Ok(convert_yaml_value_to_nu_value(&v, tag))
 }
@@ -98,28 +95,30 @@ pub fn from_yaml_string_to_value(
 fn from_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let name_span = tag.span;
     let input = args.input;
 
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let mut concat_string = String::new();
         let mut latest_tag: Option<Tag> = None;
 
         for value in values {
-            let value_tag = value.tag();
-            latest_tag = Some(value_tag.clone());
-            match value.item {
-                Value::Primitive(Primitive::String(s)) => {
+            latest_tag = Some(value.tag.clone());
+            let value_span = value.tag.span;
+
+            match &value.value {
+                UntaggedValue::Primitive(Primitive::String(s)) => {
                     concat_string.push_str(&s);
                     concat_string.push_str("\n");
                 }
                 _ => yield Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    name_span,
                     "value originates from here",
-                    &value_tag,
+                    value_span,
                 )),
 
             }
@@ -127,7 +126,7 @@ fn from_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStre
 
         match from_yaml_string_to_value(concat_string, tag.clone()) {
             Ok(x) => match x {
-                Tagged { item: Value::Table(list), .. } => {
+                Value { value: UntaggedValue::Table(list), .. } => {
                     for l in list {
                         yield ReturnSuccess::value(l);
                     }

src/commands/get.rs

@@ -7,6 +7,7 @@ use crate::utils::did_you_mean;
 use crate::ColumnPath;
 use futures_util::pin_mut;
 use log::trace;
+use nu_source::{span_for_spanned_list, PrettyDebug};
 
 pub struct Get;
 
@@ -40,31 +41,31 @@ impl WholeStreamCommand for Get {
     }
 }
 
-pub fn get_column_path(
-    path: &ColumnPath,
-    obj: &Tagged<Value>,
-) -> Result<Tagged<Value>, ShellError> {
+pub fn get_column_path(path: &ColumnPath, obj: &Value) -> Result<Value, ShellError> {
     let fields = path.clone();
 
-    let value = obj.get_data_by_column_path(
+    obj.get_data_by_column_path(
         path,
         Box::new(move |(obj_source, column_path_tried, error)| {
-            match obj_source {
-                Value::Table(rows) => {
+            match &obj_source.value {
+                UntaggedValue::Table(rows) => {
                     let total = rows.len();
                     let end_tag = match fields
                         .members()
                         .iter()
                         .nth_back(if fields.members().len() > 2 { 1 } else { 0 })
                     {
-                        Some(last_field) => last_field.span(),
-                        None => column_path_tried.span(),
+                        Some(last_field) => last_field.span,
+                        None => column_path_tried.span,
                     };
 
                     return ShellError::labeled_error_with_secondary(
                         "Row not found",
-                        format!("There isn't a row indexed at {}", **column_path_tried),
-                        column_path_tried.span(),
+                        format!(
+                            "There isn't a row indexed at {}",
+                            column_path_tried.display()
+                        ),
+                        column_path_tried.span,
                         if total == 1 {
                             format!("The table only has 1 row")
                         } else {
@@ -81,7 +82,7 @@ pub fn get_column_path(
                     return ShellError::labeled_error(
                         "Unknown column",
                         format!("did you mean '{}'?", suggestions[0].1),
-                        span_for_spanned_list(fields.members().iter().map(|p| p.span())),
+                        span_for_spanned_list(fields.members().iter().map(|p| p.span)),
                     )
                 }
                 None => {}
@@ -89,14 +90,7 @@ pub fn get_column_path(
 
             return error;
         }),
-    );
-
-    let res = match value {
-        Ok(Tagged { item: v, tag }) => Ok((v.clone()).tagged(&tag)),
-        Err(reason) => Err(reason),
-    };
-
-    res
+    )
 }
 
 pub fn get(
@@ -112,7 +106,7 @@ pub fn get(
             let mut index = 0;
 
             while let Some(row) = values.next().await {
-                shapes.add(&row.item, index);
+                shapes.add(&row, index);
                 index += 1;
             }
 
@@ -144,8 +138,8 @@ pub fn get(
 
                     match res {
                         Ok(got) => match got {
-                            Tagged {
-                                item: Value::Table(rows),
+                            Value {
+                                value: UntaggedValue::Table(rows),
                                 ..
                             } => {
                                 for item in rows {
@@ -154,8 +148,9 @@ pub fn get(
                             }
                             other => result.push_back(ReturnSuccess::value(other.clone())),
                         },
-                        Err(reason) => result
-                            .push_back(ReturnSuccess::value(Value::Error(reason).tagged_unknown())),
+                        Err(reason) => result.push_back(ReturnSuccess::value(
+                            UntaggedValue::Error(reason).into_untagged_value(),
+                        )),
                     }
                 }
 

src/commands/group_by.rs

@@ -1,7 +1,9 @@
 use crate::commands::WholeStreamCommand;
+use crate::data::base::UntaggedValue;
 use crate::data::TaggedDictBuilder;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct GroupBy;
 
@@ -41,7 +43,7 @@ pub fn group_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         if values.is_empty() {
             yield Err(ShellError::labeled_error(
@@ -62,9 +64,9 @@ pub fn group_by(
 
 pub fn group(
     column_name: &Tagged<String>,
-    values: Vec<Tagged<Value>>,
+    values: Vec<Value>,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let tag = tag.into();
 
     let mut groups = indexmap::IndexMap::new();
@@ -105,33 +107,32 @@ pub fn group(
     let mut out = TaggedDictBuilder::new(&tag);
 
     for (k, v) in groups.iter() {
-        out.insert(k, Value::table(v));
+        out.insert_untagged(k, UntaggedValue::table(v));
     }
 
-    Ok(out.into_tagged_value())
+    Ok(out.into_value())
 }
 
 #[cfg(test)]
 mod tests {
-
     use crate::commands::group_by::group;
-    use crate::data::meta::*;
-    use crate::Value;
+    use crate::data::base::{UntaggedValue, Value};
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},

src/commands/help.rs

@@ -3,6 +3,7 @@ use crate::data::{command_dict, TaggedDictBuilder};
 use crate::errors::ShellError;
 use crate::parser::registry::{self, NamedType, PositionalType};
 use crate::prelude::*;
+use nu_source::SpannedItem;
 
 pub struct Help;
 
@@ -24,13 +25,13 @@ impl PerItemCommand for Help {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         _raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         let tag = &call_info.name_tag;
 
         match call_info.args.nth(0) {
-            Some(Tagged {
-                item: Value::Primitive(Primitive::String(document)),
+            Some(Value {
+                value: UntaggedValue::Primitive(Primitive::String(document)),
                 tag,
             }) => {
                 let mut help = VecDeque::new();
@@ -41,8 +42,8 @@ impl PerItemCommand for Help {
                         let mut short_desc = TaggedDictBuilder::new(tag.clone());
                         let value = command_dict(registry.get_command(&cmd).unwrap(), tag.clone());
 
-                        short_desc.insert("name", cmd);
-                        short_desc.insert(
+                        short_desc.insert_untagged("name", cmd);
+                        short_desc.insert_untagged(
                             "description",
                             value
                                 .get_data_by_key("usage".spanned_unknown())
@@ -51,7 +52,7 @@ impl PerItemCommand for Help {
                                 .unwrap(),
                         );
 
-                        help.push_back(ReturnSuccess::value(short_desc.into_tagged_value()));
+                        help.push_back(ReturnSuccess::value(short_desc.into_value()));
                     }
                 } else {
                     if let Some(command) = registry.get_command(document) {
@@ -148,7 +149,7 @@ impl PerItemCommand for Help {
                         }
 
                         help.push_back(ReturnSuccess::value(
-                            Value::string(long_desc).tagged(tag.clone()),
+                            UntaggedValue::string(long_desc).into_value(tag.clone()),
                         ));
                     }
                 }
@@ -166,7 +167,9 @@ You can also learn more at https://book.nushell.sh"#;
 
                 let mut output_stream = VecDeque::new();
 
-                output_stream.push_back(ReturnSuccess::value(Value::string(msg).tagged(tag)));
+                output_stream.push_back(ReturnSuccess::value(
+                    UntaggedValue::string(msg).into_value(tag),
+                ));
 
                 Ok(output_stream.to_output_stream())
             }

src/commands/histogram.rs

@@ -8,6 +8,7 @@ use crate::commands::WholeStreamCommand;
 use crate::data::TaggedDictBuilder;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 use num_traits::cast::ToPrimitive;
 
 pub struct Histogram;
@@ -54,7 +55,7 @@ pub fn histogram(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let Tagged { item: group_by, .. } = column_name.clone();
 
@@ -67,8 +68,8 @@ pub fn histogram(
         let percents = percentages(&reduced, maxima, &name)?;
 
         match percents {
-            Tagged {
-                item: Value::Table(datasets),
+            Value {
+                value: UntaggedValue::Table(datasets),
                 ..
             } => {
 
@@ -84,20 +85,21 @@ pub fn histogram(
 
                 let column = (*column_name).clone();
 
-                if let Tagged { item: Value::Table(start), .. } = datasets.get(0).unwrap() {
+                if let Value { value: UntaggedValue::Table(start), .. } = datasets.get(0).unwrap() {
                     for percentage in start.into_iter() {
 
                         let mut fact = TaggedDictBuilder::new(&name);
                         let value: Tagged<String> = group_labels.get(idx).unwrap().clone();
-                        fact.insert_tagged(&column, Value::string(value.item).tagged(value.tag));
+                        fact.insert_value(&column, UntaggedValue::string(value.item).into_value(value.tag));
 
-                        if let Tagged { item: Value::Primitive(Primitive::Int(ref num)), .. } = percentage.clone() {
-                            fact.insert(&frequency_column_name, std::iter::repeat("*").take(num.to_i32().unwrap() as usize).collect::<String>());
+                        if let Value { value: UntaggedValue::Primitive(Primitive::Int(ref num)), .. } = percentage.clone() {
+                            let string = std::iter::repeat("*").take(num.to_i32().unwrap() as usize).collect::<String>();
+                            fact.insert_untagged(&frequency_column_name, UntaggedValue::string(string));
                         }
 
                         idx = idx + 1;
 
-                        yield ReturnSuccess::value(fact.into_tagged_value());
+                        yield ReturnSuccess::value(fact.into_value());
                     }
                 }
             }
@@ -108,54 +110,53 @@ pub fn histogram(
     Ok(stream.to_output_stream())
 }
 
-fn percentages(
-    values: &Tagged<Value>,
-    max: Tagged<Value>,
-    tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+fn percentages(values: &Value, max: Value, tag: impl Into<Tag>) -> Result<Value, ShellError> {
     let tag = tag.into();
 
-    let results: Tagged<Value> = match values {
-        Tagged {
-            item: Value::Table(datasets),
+    let results: Value = match values {
+        Value {
+            value: UntaggedValue::Table(datasets),
             ..
         } => {
             let datasets: Vec<_> = datasets
                 .into_iter()
                 .map(|subsets| match subsets {
-                    Tagged {
-                        item: Value::Table(data),
+                    Value {
+                        value: UntaggedValue::Table(data),
                         ..
                     } => {
-                        let data = data
-                            .into_iter()
-                            .map(|d| match d {
-                                Tagged {
-                                    item: Value::Primitive(Primitive::Int(n)),
-                                    ..
-                                } => {
-                                    let max = match max {
-                                        Tagged {
-                                            item: Value::Primitive(Primitive::Int(ref maxima)),
+                        let data =
+                                data.into_iter()
+                                    .map(|d| match d {
+                                        Value {
+                                            value: UntaggedValue::Primitive(Primitive::Int(n)),
                                             ..
-                                        } => maxima.to_i32().unwrap(),
-                                        _ => 0,
-                                    };
+                                        } => {
+                                            let max = match max {
+                                                Value {
+                                                    value:
+                                                        UntaggedValue::Primitive(Primitive::Int(
+                                                            ref maxima,
+                                                        )),
+                                                    ..
+                                                } => maxima.to_i32().unwrap(),
+                                                _ => 0,
+                                            };
 
-                                    let n = { n.to_i32().unwrap() * 100 / max };
+                                            let n = { n.to_i32().unwrap() * 100 / max };
 
-                                    Value::number(n).tagged(&tag)
-                                }
-                                _ => Value::number(0).tagged(&tag),
-                            })
-                            .collect::<Vec<_>>();
-                        Value::Table(data).tagged(&tag)
+                                            UntaggedValue::number(n).into_value(&tag)
+                                        }
+                                        _ => UntaggedValue::number(0).into_value(&tag),
+                                    })
+                                    .collect::<Vec<_>>();
+                        UntaggedValue::Table(data).into_value(&tag)
                     }
-                    _ => Value::Table(vec![]).tagged(&tag),
+                    _ => UntaggedValue::Table(vec![]).into_value(&tag),
                 })
                 .collect();
 
-            Value::Table(datasets).tagged(&tag)
+            UntaggedValue::Table(datasets).into_value(&tag)
         }
         other => other.clone(),
     };

src/commands/history.rs

@@ -26,7 +26,7 @@ impl PerItemCommand for History {
         call_info: &CallInfo,
         _registry: &CommandRegistry,
         _raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         let tag = call_info.name_tag.clone();
 
@@ -37,7 +37,7 @@ impl PerItemCommand for History {
                 let reader = BufReader::new(file);
                 for line in reader.lines() {
                     if let Ok(line) = line {
-                        yield ReturnSuccess::value(Value::string(line).tagged(tag.clone()));
+                        yield ReturnSuccess::value(UntaggedValue::string(line).into_value(tag.clone()));
                     }
                 }
             } else {

src/commands/last.rs

@@ -2,6 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::parser::CommandRegistry;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct Last;
 
@@ -50,7 +51,7 @@ fn last(LastArgs { rows }: LastArgs, context: RunnableContext) -> Result<OutputS
         if count < v.len() {
             let k = v.len() - count;
             for x in v[k..].iter() {
-                let y: Tagged<Value> = x.clone();
+                let y: Value = x.clone();
                 yield ReturnSuccess::value(y)
             }
         }

src/commands/lines.rs

@@ -1,5 +1,5 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, Value};
+use crate::data::Primitive;
 use crate::errors::ShellError;
 use crate::prelude::*;
 use log::trace;
@@ -33,12 +33,13 @@ impl WholeStreamCommand for Lines {
 fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let tag = args.name_tag();
+    let name_span = tag.span;
     let input = args.input;
 
     let stream = input
         .values
-        .map(move |v| match v.item {
-            Value::Primitive(Primitive::String(s)) => {
+        .map(move |v| match v.value {
+            UntaggedValue::Primitive(Primitive::String(s)) => {
                 let split_result: Vec<_> = s.lines().filter(|s| s.trim() != "").collect();
 
                 trace!("split result = {:?}", split_result);
@@ -46,19 +47,21 @@ fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
                 let mut result = VecDeque::new();
                 for s in split_result {
                     result.push_back(ReturnSuccess::value(
-                        Value::Primitive(Primitive::String(s.into())).tagged_unknown(),
+                        UntaggedValue::Primitive(Primitive::String(s.into())).into_untagged_value(),
                     ));
                 }
                 result
             }
             _ => {
                 let mut result = VecDeque::new();
+                let value_span = v.tag.span;
+
                 result.push_back(Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &tag,
+                    name_span,
                     "value originates from here",
-                    v.tag(),
+                    value_span,
                 )));
                 result
             }

src/commands/ls.rs

@@ -1,6 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct LS;

src/commands/map_max_by.rs

@@ -1,7 +1,9 @@
 use crate::commands::WholeStreamCommand;
 use crate::parser::hir::SyntaxShape;
 use crate::prelude::*;
+use nu_source::Tagged;
 use num_traits::cast::ToPrimitive;
+
 pub struct MapMaxBy;
 
 #[derive(Deserialize)]
@@ -40,7 +42,7 @@ pub fn map_max_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
 
         if values.is_empty() {
@@ -68,27 +70,27 @@ pub fn map_max_by(
 }
 
 pub fn map_max(
-    values: &Tagged<Value>,
+    values: &Value,
     _map_by_column_name: Option<String>,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let tag = tag.into();
 
-    let results: Tagged<Value> = match values {
-        Tagged {
-            item: Value::Table(datasets),
+    let results: Value = match values {
+        Value {
+            value: UntaggedValue::Table(datasets),
             ..
         } => {
             let datasets: Vec<_> = datasets
                 .into_iter()
                 .map(|subsets| match subsets {
-                    Tagged {
-                        item: Value::Table(data),
+                    Value {
+                        value: UntaggedValue::Table(data),
                         ..
                     } => {
                         let data = data.into_iter().fold(0, |acc, value| match value {
-                            Tagged {
-                                item: Value::Primitive(Primitive::Int(n)),
+                            Value {
+                                value: UntaggedValue::Primitive(Primitive::Int(n)),
                                 ..
                             } => {
                                 if n.to_i32().unwrap() > acc {
@@ -99,15 +101,15 @@ pub fn map_max(
                             }
                             _ => acc,
                         });
-                        Value::number(data).tagged(&tag)
+                        UntaggedValue::number(data).into_value(&tag)
                     }
-                    _ => Value::number(0).tagged(&tag),
+                    _ => UntaggedValue::number(0).into_value(&tag),
                 })
                 .collect();
 
             let datasets = datasets.iter().fold(0, |max, value| match value {
-                Tagged {
-                    item: Value::Primitive(Primitive::Int(n)),
+                Value {
+                    value: UntaggedValue::Primitive(Primitive::Int(n)),
                     ..
                 } => {
                     if n.to_i32().unwrap() > max {
@@ -118,9 +120,9 @@ pub fn map_max(
                 }
                 _ => max,
             });
-            Value::number(datasets).tagged(&tag)
+            UntaggedValue::number(datasets).into_value(&tag)
         }
-        _ => Value::number(-1).tagged(&tag),
+        _ => UntaggedValue::number(-1).into_value(&tag),
     };
 
     Ok(results)
@@ -134,28 +136,28 @@ mod tests {
     use crate::commands::map_max_by::map_max;
     use crate::commands::reduce_by::reduce;
     use crate::commands::t_sort_by::t_sort;
-    use crate::data::meta::*;
     use crate::prelude::*;
     use crate::Value;
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn int(s: impl Into<BigInt>) -> Tagged<Value> {
-        Value::int(s).tagged_unknown()
+    fn int(s: impl Into<BigInt>) -> Value {
+        UntaggedValue::int(s).into_untagged_value()
     }
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn nu_releases_evaluated_by_default_one() -> Tagged<Value> {
+    fn nu_releases_evaluated_by_default_one() -> Value {
         evaluate(&nu_releases_sorted_by_date(), None, Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_reduced_by_sum() -> Tagged<Value> {
+    fn nu_releases_reduced_by_sum() -> Value {
         reduce(
             &nu_releases_evaluated_by_default_one(),
             Some(String::from("sum")),
@@ -164,7 +166,7 @@ mod tests {
         .unwrap()
     }
 
-    fn nu_releases_sorted_by_date() -> Tagged<Value> {
+    fn nu_releases_sorted_by_date() -> Value {
         let key = String::from("date");
 
         t_sort(
@@ -176,12 +178,12 @@ mod tests {
         .unwrap()
     }
 
-    fn nu_releases_grouped_by_date() -> Tagged<Value> {
+    fn nu_releases_grouped_by_date() -> Value {
         let key = String::from("date").tagged_unknown();
         group(&key, nu_releases_commiters(), Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},

src/commands/mkdir.rs

@@ -2,6 +2,7 @@ use crate::commands::command::RunnablePerItemContext;
 use crate::errors::ShellError;
 use crate::parser::registry::{CommandRegistry, Signature};
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct Mkdir;
@@ -29,7 +30,7 @@ impl PerItemCommand for Mkdir {
         call_info: &CallInfo,
         _registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         call_info.process(&raw_args.shell_manager, mkdir)?.run()
     }

src/commands/mv.rs

@@ -3,6 +3,7 @@ use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::{CommandRegistry, Signature};
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct Move;
@@ -41,7 +42,7 @@ impl PerItemCommand for Move {
         call_info: &CallInfo,
         _registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         call_info.process(&raw_args.shell_manager, mv)?.run()
     }

src/commands/nth.rs

@@ -2,6 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::parser::CommandRegistry;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 struct NthArgs {

src/commands/open.rs

@@ -1,11 +1,11 @@
 use crate::commands::UnevaluatedCallInfo;
-use crate::context::AnchorLocation;
-use crate::data::meta::Span;
 use crate::data::Value;
 use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::Signature;
 use crate::prelude::*;
+use nu_source::AnchorLocation;
+use nu_source::Span;
 use std::path::{Path, PathBuf};
 pub struct Open;
 
@@ -33,7 +33,7 @@ impl PerItemCommand for Open {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         run(call_info, registry, raw_args)
     }
@@ -48,15 +48,14 @@ fn run(
     let cwd = PathBuf::from(shell_manager.path());
     let full_path = PathBuf::from(cwd);
 
-    let path = match call_info.args.nth(0).ok_or_else(|| {
+    let path = call_info.args.nth(0).ok_or_else(|| {
         ShellError::labeled_error(
             "No file or directory specified",
             "for command",
             &call_info.name_tag,
         )
-    })? {
-        file => file,
-    };
+    })?;
+
     let path_buf = path.as_path()?;
     let path_str = path_buf.display().to_string();
     let path_span = path.tag.span;
@@ -82,7 +81,7 @@ fn run(
             file_extension.or(path_str.split('.').last().map(String::from))
         };
 
-        let tagged_contents = contents.tagged(&contents_tag);
+        let tagged_contents = contents.into_value(&contents_tag);
 
         if let Some(extension) = file_extension {
             let command_name = format!("from-{}", extension);
@@ -95,7 +94,8 @@ fn run(
                         args: crate::parser::hir::Call {
                             head: raw_args.call_info.args.head,
                             positional: None,
-                            named: None
+                            named: None,
+                            span: Span::unknown()
                         },
                         source: raw_args.call_info.source,
                         name_tag: raw_args.call_info.name_tag,
@@ -105,13 +105,13 @@ fn run(
                 let result_vec: Vec<Result<ReturnSuccess, ShellError>> = result.drain_vec().await;
                 for res in result_vec {
                     match res {
-                        Ok(ReturnSuccess::Value(Tagged { item: Value::Table(list), ..})) => {
+                        Ok(ReturnSuccess::Value(Value { value: UntaggedValue::Table(list), ..})) => {
                             for l in list {
                                 yield Ok(ReturnSuccess::Value(l));
                             }
                         }
-                        Ok(ReturnSuccess::Value(Tagged { item, .. })) => {
-                            yield Ok(ReturnSuccess::Value(Tagged { item, tag: contents_tag.clone() }));
+                        Ok(ReturnSuccess::Value(Value { value, .. })) => {
+                            yield Ok(ReturnSuccess::Value(Value { value, tag: contents_tag.clone() }));
                         }
                         x => yield x,
                     }
@@ -131,7 +131,7 @@ pub async fn fetch(
     cwd: &PathBuf,
     location: &str,
     span: Span,
-) -> Result<(Option<String>, Value, Tag), ShellError> {
+) -> Result<(Option<String>, UntaggedValue, Tag), ShellError> {
     let mut cwd = cwd.clone();
 
     cwd.push(Path::new(location));
@@ -141,7 +141,7 @@ pub async fn fetch(
                 Ok(s) => Ok((
                     cwd.extension()
                         .map(|name| name.to_string_lossy().to_string()),
-                    Value::string(s),
+                    UntaggedValue::string(s),
                     Tag {
                         span,
                         anchor: Some(AnchorLocation::File(cwd.to_string_lossy().to_string())),
@@ -159,7 +159,7 @@ pub async fn fetch(
                                     Ok(s) => Ok((
                                         cwd.extension()
                                             .map(|name| name.to_string_lossy().to_string()),
-                                        Value::string(s),
+                                        UntaggedValue::string(s),
                                         Tag {
                                             span,
                                             anchor: Some(AnchorLocation::File(
@@ -169,7 +169,7 @@ pub async fn fetch(
                                     )),
                                     Err(_) => Ok((
                                         None,
-                                        Value::binary(bytes),
+                                        UntaggedValue::binary(bytes),
                                         Tag {
                                             span,
                                             anchor: Some(AnchorLocation::File(
@@ -181,7 +181,7 @@ pub async fn fetch(
                             } else {
                                 Ok((
                                     None,
-                                    Value::binary(bytes),
+                                    UntaggedValue::binary(bytes),
                                     Tag {
                                         span,
                                         anchor: Some(AnchorLocation::File(
@@ -200,7 +200,7 @@ pub async fn fetch(
                                     Ok(s) => Ok((
                                         cwd.extension()
                                             .map(|name| name.to_string_lossy().to_string()),
-                                        Value::string(s),
+                                        UntaggedValue::string(s),
                                         Tag {
                                             span,
                                             anchor: Some(AnchorLocation::File(
@@ -210,7 +210,7 @@ pub async fn fetch(
                                     )),
                                     Err(_) => Ok((
                                         None,
-                                        Value::binary(bytes),
+                                        UntaggedValue::binary(bytes),
                                         Tag {
                                             span,
                                             anchor: Some(AnchorLocation::File(
@@ -222,7 +222,7 @@ pub async fn fetch(
                             } else {
                                 Ok((
                                     None,
-                                    Value::binary(bytes),
+                                    UntaggedValue::binary(bytes),
                                     Tag {
                                         span,
                                         anchor: Some(AnchorLocation::File(
@@ -234,7 +234,7 @@ pub async fn fetch(
                         }
                         _ => Ok((
                             None,
-                            Value::binary(bytes),
+                            UntaggedValue::binary(bytes),
                             Tag {
                                 span,
                                 anchor: Some(AnchorLocation::File(

src/commands/pick.rs

@@ -3,6 +3,7 @@ use crate::context::CommandRegistry;
 use crate::data::base::select_fields;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 struct PickArgs {
@@ -49,7 +50,7 @@ fn pick(
 
     let objects = input
         .values
-        .map(move |value| select_fields(&value.item, &fields, value.tag()));
+        .map(move |value| select_fields(&value, &fields, value.tag.clone()));
 
     Ok(objects.from_input_stream())
 }

src/commands/pivot.rs

@@ -2,6 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::prelude::*;
 use crate::TaggedDictBuilder;
+use nu_source::{SpannedItem, Tagged};
 
 pub struct Pivot;
 
@@ -42,7 +43,7 @@ impl WholeStreamCommand for Pivot {
     }
 }
 
-fn merge_descriptors(values: &[Tagged<Value>]) -> Vec<String> {
+fn merge_descriptors(values: &[Value]) -> Vec<String> {
     let mut ret = vec![];
     for value in values {
         for desc in value.data_descriptors() {
@@ -110,23 +111,23 @@ pub fn pivot(args: PivotArgs, context: RunnableContext) -> Result<OutputStream,
             let mut dict = TaggedDictBuilder::new(&context.name);
 
             if !args.ignore_titles && !args.header_row {
-                dict.insert(headers[column_num].clone(), Value::string(desc.clone()));
+                dict.insert_untagged(headers[column_num].clone(), UntaggedValue::string(desc.clone()));
                 column_num += 1
             }
 
             for i in input.clone() {
                 match i.get_data_by_key(desc[..].spanned_unknown()) {
                     Some(x) => {
-                        dict.insert_tagged(headers[column_num].clone(), x.clone());
+                        dict.insert_value(headers[column_num].clone(), x.clone());
                     }
                     _ => {
-                        dict.insert(headers[column_num].clone(), Value::nothing());
+                        dict.insert_untagged(headers[column_num].clone(), UntaggedValue::nothing());
                     }
                 }
                 column_num += 1;
             }
 
-            yield ReturnSuccess::value(dict.into_tagged_value());
+            yield ReturnSuccess::value(dict.into_value());
         }
 
 

src/commands/plugin.rs

@@ -79,11 +79,11 @@ pub fn filter_plugin(
         .spawn()
         .expect("Failed to spawn child process");
 
-    let mut bos: VecDeque<Tagged<Value>> = VecDeque::new();
-    bos.push_back(Value::Primitive(Primitive::BeginningOfStream).tagged_unknown());
+    let mut bos: VecDeque<Value> = VecDeque::new();
+    bos.push_back(UntaggedValue::Primitive(Primitive::BeginningOfStream).into_untagged_value());
 
-    let mut eos: VecDeque<Tagged<Value>> = VecDeque::new();
-    eos.push_back(Value::Primitive(Primitive::EndOfStream).tagged_unknown());
+    let mut eos: VecDeque<Value> = VecDeque::new();
+    eos.push_back(UntaggedValue::Primitive(Primitive::EndOfStream).into_untagged_value());
 
     let call_info = args.call_info.clone();
 
@@ -93,8 +93,8 @@ pub fn filter_plugin(
         .chain(args.input.values)
         .chain(eos)
         .map(move |v| match v {
-            Tagged {
-                item: Value::Primitive(Primitive::BeginningOfStream),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::BeginningOfStream),
                 ..
             } => {
                 let stdin = child.stdin.as_mut().expect("Failed to open stdin");
@@ -146,8 +146,8 @@ pub fn filter_plugin(
                     }
                 }
             }
-            Tagged {
-                item: Value::Primitive(Primitive::EndOfStream),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::EndOfStream),
                 ..
             } => {
                 let stdin = child.stdin.as_mut().expect("Failed to open stdin");
@@ -298,7 +298,7 @@ pub fn sink_plugin(
     let call_info = args.call_info.clone();
 
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         let request = JsonRpc::new("sink", (call_info.clone(), input));
         let request_raw = serde_json::to_string(&request).unwrap();
@@ -315,7 +315,7 @@ pub fn sink_plugin(
 
         // Needed for async_stream to type check
         if false {
-            yield ReturnSuccess::value(Value::nothing().tagged_unknown());
+            yield ReturnSuccess::value(UntaggedValue::nothing().into_untagged_value());
         }
     };
     Ok(OutputStream::new(stream))

src/commands/post.rs

@@ -1,12 +1,12 @@
 use crate::commands::UnevaluatedCallInfo;
-use crate::context::AnchorLocation;
-use crate::data::Value;
+use crate::data::base::{UntaggedValue, Value};
 use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::Signature;
 use crate::prelude::*;
 use base64::encode;
 use mime::Mime;
+use nu_source::AnchorLocation;
 use std::path::PathBuf;
 use std::str::FromStr;
 use surf::mime;
@@ -55,7 +55,7 @@ impl PerItemCommand for Post {
         call_info: &CallInfo,
         registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         run(call_info, registry, raw_args)
     }
@@ -74,6 +74,7 @@ fn run(
         })? {
             file => file.clone(),
         };
+    let path_tag = path.tag.clone();
     let body =
         match call_info.args.nth(1).ok_or_else(|| {
             ShellError::labeled_error("No body specified", "for command", &name_tag)
@@ -81,7 +82,6 @@ fn run(
             file => file.clone(),
         };
     let path_str = path.as_string()?;
-    let path_span = path.tag();
     let has_raw = call_info.args.has("raw");
     let user = call_info.args.get("user").map(|x| x.as_string().unwrap());
     let password = call_info
@@ -95,7 +95,7 @@ fn run(
 
     let stream = async_stream! {
         let (file_extension, contents, contents_tag) =
-            post(&path_str, &body, user, password, &headers, path_span, &registry, &raw_args).await.unwrap();
+            post(&path_str, &body, user, password, &headers, path_tag.clone(), &registry, &raw_args).await.unwrap();
 
         let file_extension = if has_raw {
             None
@@ -105,7 +105,7 @@ fn run(
             file_extension.or(path_str.split('.').last().map(String::from))
         };
 
-        let tagged_contents = contents.tagged(&contents_tag);
+        let tagged_contents = contents.into_value(&contents_tag);
 
         if let Some(extension) = file_extension {
             let command_name = format!("from-{}", extension);
@@ -118,7 +118,8 @@ fn run(
                         args: crate::parser::hir::Call {
                             head: raw_args.call_info.args.head,
                             positional: None,
-                            named: None
+                            named: None,
+                            span: Span::unknown()
                         },
                         source: raw_args.call_info.source,
                         name_tag: raw_args.call_info.name_tag,
@@ -128,13 +129,13 @@ fn run(
                 let result_vec: Vec<Result<ReturnSuccess, ShellError>> = result.drain_vec().await;
                 for res in result_vec {
                     match res {
-                        Ok(ReturnSuccess::Value(Tagged { item: Value::Table(list), ..})) => {
+                        Ok(ReturnSuccess::Value(Value { value: UntaggedValue::Table(list), ..})) => {
                             for l in list {
                                 yield Ok(ReturnSuccess::Value(l));
                             }
                         }
-                        Ok(ReturnSuccess::Value(Tagged { item, .. })) => {
-                            yield Ok(ReturnSuccess::Value(Tagged { item, tag: contents_tag.clone() }));
+                        Ok(ReturnSuccess::Value(Value { value, .. })) => {
+                            yield Ok(ReturnSuccess::Value(Value { value, tag: contents_tag.clone() }));
                         }
                         x => yield x,
                     }
@@ -180,11 +181,11 @@ fn extract_header_value(call_info: &CallInfo, key: &str) -> Result<Option<String
     if call_info.args.has(key) {
         let tagged = call_info.args.get(key);
         let val = match tagged {
-            Some(Tagged {
-                item: Value::Primitive(Primitive::String(s)),
+            Some(Value {
+                value: UntaggedValue::Primitive(Primitive::String(s)),
                 ..
             }) => s.clone(),
-            Some(Tagged { tag, .. }) => {
+            Some(Value { tag, .. }) => {
                 return Err(ShellError::labeled_error(
                     format!("{} not in expected format.  Expected string.", key),
                     "post error",
@@ -207,14 +208,14 @@ fn extract_header_value(call_info: &CallInfo, key: &str) -> Result<Option<String
 
 pub async fn post(
     location: &str,
-    body: &Tagged<Value>,
+    body: &Value,
     user: Option<String>,
     password: Option<String>,
     headers: &Vec<HeaderKind>,
     tag: Tag,
     registry: &CommandRegistry,
     raw_args: &RawCommandArgs,
-) -> Result<(Option<String>, Value, Tag), ShellError> {
+) -> Result<(Option<String>, UntaggedValue, Tag), ShellError> {
     let registry = registry.clone();
     let raw_args = raw_args.clone();
     if location.starts_with("http:") || location.starts_with("https:") {
@@ -224,8 +225,8 @@ pub async fn post(
             _ => None,
         };
         let response = match body {
-            Tagged {
-                item: Value::Primitive(Primitive::String(body_str)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::String(body_str)),
                 ..
             } => {
                 let mut s = surf::post(location).body_string(body_str.to_string());
@@ -241,8 +242,8 @@ pub async fn post(
                 }
                 s.await
             }
-            Tagged {
-                item: Value::Primitive(Primitive::Binary(b)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Binary(b)),
                 ..
             } => {
                 let mut s = surf::post(location).body_bytes(b);
@@ -251,7 +252,7 @@ pub async fn post(
                 }
                 s.await
             }
-            Tagged { item, tag } => {
+            Value { value, tag } => {
                 if let Some(converter) = registry.get_command("to-json") {
                     let new_args = RawCommandArgs {
                         host: raw_args.host,
@@ -262,13 +263,14 @@ pub async fn post(
                                 head: raw_args.call_info.args.head,
                                 positional: None,
                                 named: None,
+                                span: Span::unknown(),
                             },
                             source: raw_args.call_info.source,
                             name_tag: raw_args.call_info.name_tag,
                         },
                     };
                     let mut result = converter.run(
-                        new_args.with_input(vec![item.clone().tagged(tag.clone())]),
+                        new_args.with_input(vec![value.clone().into_value(tag.clone())]),
                         &registry,
                     );
                     let result_vec: Vec<Result<ReturnSuccess, ShellError>> =
@@ -276,8 +278,8 @@ pub async fn post(
                     let mut result_string = String::new();
                     for res in result_vec {
                         match res {
-                            Ok(ReturnSuccess::Value(Tagged {
-                                item: Value::Primitive(Primitive::String(s)),
+                            Ok(ReturnSuccess::Value(Value {
+                                value: UntaggedValue::Primitive(Primitive::String(s)),
                                 ..
                             })) => {
                                 result_string.push_str(&s);
@@ -314,7 +316,7 @@ pub async fn post(
                     match (content_type.type_(), content_type.subtype()) {
                         (mime::APPLICATION, mime::XML) => Ok((
                             Some("xml".to_string()),
-                            Value::string(r.body_string().await.map_err(|_| {
+                            UntaggedValue::string(r.body_string().await.map_err(|_| {
                                 ShellError::labeled_error(
                                     "Could not load text from remote url",
                                     "could not load",
@@ -328,7 +330,7 @@ pub async fn post(
                         )),
                         (mime::APPLICATION, mime::JSON) => Ok((
                             Some("json".to_string()),
-                            Value::string(r.body_string().await.map_err(|_| {
+                            UntaggedValue::string(r.body_string().await.map_err(|_| {
                                 ShellError::labeled_error(
                                     "Could not load text from remote url",
                                     "could not load",
@@ -350,7 +352,7 @@ pub async fn post(
                             })?;
                             Ok((
                                 None,
-                                Value::binary(buf),
+                                UntaggedValue::binary(buf),
                                 Tag {
                                     anchor: Some(AnchorLocation::Url(location.to_string())),
                                     span: tag.span,
@@ -367,7 +369,7 @@ pub async fn post(
                             })?;
                             Ok((
                                 Some(image_ty.to_string()),
-                                Value::binary(buf),
+                                UntaggedValue::binary(buf),
                                 Tag {
                                     anchor: Some(AnchorLocation::Url(location.to_string())),
                                     span: tag.span,
@@ -376,7 +378,7 @@ pub async fn post(
                         }
                         (mime::TEXT, mime::HTML) => Ok((
                             Some("html".to_string()),
-                            Value::string(r.body_string().await.map_err(|_| {
+                            UntaggedValue::string(r.body_string().await.map_err(|_| {
                                 ShellError::labeled_error(
                                     "Could not load text from remote url",
                                     "could not load",
@@ -402,7 +404,7 @@ pub async fn post(
 
                             Ok((
                                 path_extension,
-                                Value::string(r.body_string().await.map_err(|_| {
+                                UntaggedValue::string(r.body_string().await.map_err(|_| {
                                     ShellError::labeled_error(
                                         "Could not load text from remote url",
                                         "could not load",
@@ -417,7 +419,7 @@ pub async fn post(
                         }
                         (ty, sub_ty) => Ok((
                             None,
-                            Value::string(format!(
+                            UntaggedValue::string(format!(
                                 "Not yet supported MIME type: {} {}",
                                 ty, sub_ty
                             )),
@@ -430,7 +432,7 @@ pub async fn post(
                 }
                 None => Ok((
                     None,
-                    Value::string(format!("No content type found")),
+                    UntaggedValue::string(format!("No content type found")),
                     Tag {
                         anchor: Some(AnchorLocation::Url(location.to_string())),
                         span: tag.span,

src/commands/prepend.rs

@@ -5,7 +5,7 @@ use crate::prelude::*;
 
 #[derive(Deserialize)]
 struct PrependArgs {
-    row: Tagged<Value>,
+    row: Value,
 }
 
 pub struct Prepend;
@@ -40,7 +40,7 @@ fn prepend(
     PrependArgs { row }: PrependArgs,
     RunnableContext { input, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
-    let mut prepend: VecDeque<Tagged<Value>> = VecDeque::new();
+    let mut prepend: VecDeque<Value> = VecDeque::new();
     prepend.push_back(row);
 
     Ok(OutputStream::from_input(prepend.chain(input.values)))

src/commands/reduce_by.rs

@@ -1,7 +1,9 @@
 use crate::commands::WholeStreamCommand;
 use crate::parser::hir::SyntaxShape;
 use crate::prelude::*;
+use nu_source::Tagged;
 use num_traits::cast::ToPrimitive;
+
 pub struct ReduceBy;
 
 #[derive(Deserialize)]
@@ -40,7 +42,7 @@ pub fn reduce_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         if values.is_empty() {
             yield Err(ShellError::labeled_error(
@@ -66,10 +68,10 @@ pub fn reduce_by(
     Ok(stream.to_output_stream())
 }
 
-fn sum(data: Vec<Tagged<Value>>) -> i32 {
+fn sum(data: Vec<Value>) -> i32 {
     data.into_iter().fold(0, |acc, value| match value {
-        Tagged {
-            item: Value::Primitive(Primitive::Int(n)),
+        Value {
+            value: UntaggedValue::Primitive(Primitive::Int(n)),
             ..
         } => acc + n.to_i32().unwrap(),
         _ => acc,
@@ -78,15 +80,15 @@ fn sum(data: Vec<Tagged<Value>>) -> i32 {
 
 fn formula(
     acc_begin: i32,
-    calculator: Box<dyn Fn(Vec<Tagged<Value>>) -> i32 + 'static>,
-) -> Box<dyn Fn(i32, Vec<Tagged<Value>>) -> i32 + 'static> {
+    calculator: Box<dyn Fn(Vec<Value>) -> i32 + 'static>,
+) -> Box<dyn Fn(i32, Vec<Value>) -> i32 + 'static> {
     Box::new(move |acc, datax| -> i32 {
         let result = acc * acc_begin;
         result + calculator(datax)
     })
 }
 
-fn reducer_for(command: Reduce) -> Box<dyn Fn(i32, Vec<Tagged<Value>>) -> i32 + 'static> {
+fn reducer_for(command: Reduce) -> Box<dyn Fn(i32, Vec<Value>) -> i32 + 'static> {
     match command {
         Reduce::Sum | Reduce::Default => Box::new(formula(0, Box::new(sum))),
     }
@@ -98,10 +100,10 @@ pub enum Reduce {
 }
 
 pub fn reduce(
-    values: &Tagged<Value>,
+    values: &Value,
     reducer: Option<String>,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let tag = tag.into();
 
     let reduce_with = match reducer {
@@ -109,9 +111,9 @@ pub fn reduce(
         Some(_) | None => reducer_for(Reduce::Default),
     };
 
-    let results: Tagged<Value> = match values {
-        Tagged {
-            item: Value::Table(datasets),
+    let results: Value = match values {
+        Value {
+            value: UntaggedValue::Table(datasets),
             ..
         } => {
             let datasets: Vec<_> = datasets
@@ -119,35 +121,35 @@ pub fn reduce(
                 .map(|subsets| {
                     let mut acc = 0;
                     match subsets {
-                        Tagged {
-                            item: Value::Table(data),
+                        Value {
+                            value: UntaggedValue::Table(data),
                             ..
                         } => {
                             let data = data
                                 .into_iter()
                                 .map(|d| {
-                                    if let Tagged {
-                                        item: Value::Table(x),
+                                    if let Value {
+                                        value: UntaggedValue::Table(x),
                                         ..
                                     } = d
                                     {
                                         acc = reduce_with(acc, x.clone());
-                                        Value::number(acc).tagged(&tag)
+                                        UntaggedValue::number(acc).into_value(&tag)
                                     } else {
-                                        Value::number(0).tagged(&tag)
+                                        UntaggedValue::number(0).into_value(&tag)
                                     }
                                 })
                                 .collect::<Vec<_>>();
-                            Value::Table(data).tagged(&tag)
+                            UntaggedValue::Table(data).into_value(&tag)
                         }
-                        _ => Value::Table(vec![]).tagged(&tag),
+                        _ => UntaggedValue::Table(vec![]).into_value(&tag),
                     }
                 })
                 .collect();
 
-            Value::Table(datasets).tagged(&tag)
+            UntaggedValue::Table(datasets).into_value(&tag)
         }
-        _ => Value::Table(vec![]).tagged(&tag),
+        _ => UntaggedValue::Table(vec![]).into_value(&tag),
     };
 
     Ok(results)
@@ -160,28 +162,28 @@ mod tests {
     use crate::commands::group_by::group;
     use crate::commands::reduce_by::{reduce, reducer_for, Reduce};
     use crate::commands::t_sort_by::t_sort;
-    use crate::data::meta::*;
     use crate::prelude::*;
     use crate::Value;
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn int(s: impl Into<BigInt>) -> Tagged<Value> {
-        Value::int(s).tagged_unknown()
+    fn int(s: impl Into<BigInt>) -> Value {
+        UntaggedValue::int(s).into_untagged_value()
     }
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn nu_releases_sorted_by_date() -> Tagged<Value> {
+    fn nu_releases_sorted_by_date() -> Value {
         let key = String::from("date");
 
         t_sort(
@@ -193,16 +195,16 @@ mod tests {
         .unwrap()
     }
 
-    fn nu_releases_evaluated_by_default_one() -> Tagged<Value> {
+    fn nu_releases_evaluated_by_default_one() -> Value {
         evaluate(&nu_releases_sorted_by_date(), None, Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_grouped_by_date() -> Tagged<Value> {
+    fn nu_releases_grouped_by_date() -> Value {
         let key = String::from("date").tagged_unknown();
         group(&key, nu_releases_commiters(), Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},

src/commands/reject.rs

@@ -2,6 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::data::base::reject_fields;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 pub struct RejectArgs {
@@ -48,7 +49,7 @@ fn reject(
 
     let stream = input
         .values
-        .map(move |item| reject_fields(&item, &fields, item.tag()).into_tagged_value());
+        .map(move |item| reject_fields(&item, &fields, &item.tag));
 
     Ok(stream.from_input_stream())
 }

src/commands/rm.rs

@@ -3,6 +3,7 @@ use crate::errors::ShellError;
 use crate::parser::hir::SyntaxShape;
 use crate::parser::registry::{CommandRegistry, Signature};
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::PathBuf;
 
 pub struct Remove;
@@ -38,7 +39,7 @@ impl PerItemCommand for Remove {
         call_info: &CallInfo,
         _registry: &CommandRegistry,
         raw_args: &RawCommandArgs,
-        _input: Tagged<Value>,
+        _input: Value,
     ) -> Result<OutputStream, ShellError> {
         call_info.process(&raw_args.shell_manager, rm)?.run()
     }

src/commands/save.rs

@@ -2,6 +2,7 @@ use crate::commands::{UnevaluatedCallInfo, WholeStreamCommand};
 use crate::data::Value;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 use std::path::{Path, PathBuf};
 
 pub struct Save;
@@ -11,8 +12,8 @@ macro_rules! process_string {
         let mut result_string = String::new();
         for res in $input {
             match res {
-                Tagged {
-                    item: Value::Primitive(Primitive::String(s)),
+                Value {
+                    value: UntaggedValue::Primitive(Primitive::String(s)),
                     ..
                 } => {
                     result_string.push_str(&s);
@@ -35,8 +36,8 @@ macro_rules! process_string_return_success {
         let mut result_string = String::new();
         for res in $result_vec {
             match res {
-                Ok(ReturnSuccess::Value(Tagged {
-                    item: Value::Primitive(Primitive::String(s)),
+                Ok(ReturnSuccess::Value(Value {
+                    value: UntaggedValue::Primitive(Primitive::String(s)),
                     ..
                 })) => {
                     result_string.push_str(&s);
@@ -59,8 +60,8 @@ macro_rules! process_binary_return_success {
         let mut result_binary: Vec<u8> = Vec::new();
         for res in $result_vec {
             match res {
-                Ok(ReturnSuccess::Value(Tagged {
-                    item: Value::Primitive(Primitive::Binary(b)),
+                Ok(ReturnSuccess::Value(Value {
+                    value: UntaggedValue::Primitive(Primitive::Binary(b)),
                     ..
                 })) => {
                     for u in b.into_iter() {
@@ -133,11 +134,11 @@ fn save(
     let name_tag = name.clone();
 
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = input.values.collect().await;
+        let input: Vec<Value> = input.values.collect().await;
         if path.is_none() {
             // If there is no filename, check the metadata for the anchor filename
             if input.len() > 0 {
-                let anchor = input[0].anchor();
+                let anchor = input[0].tag.anchor();
                 match anchor {
                     Some(path) => match path {
                         AnchorLocation::File(file) => {
@@ -187,7 +188,8 @@ fn save(
                                 args: crate::parser::hir::Call {
                                     head: raw_args.call_info.args.head,
                                     positional: None,
-                                    named: None
+                                    named: None,
+                                    span: Span::unknown()
                                 },
                                 source: raw_args.call_info.source,
                                 name_tag: raw_args.call_info.name_tag,
@@ -224,7 +226,7 @@ fn save(
     Ok(OutputStream::new(stream))
 }
 
-fn string_from(input: &Vec<Tagged<Value>>) -> String {
+fn string_from(input: &Vec<Value>) -> String {
     let mut save_data = String::new();
 
     if input.len() > 0 {

src/commands/shells.rs

@@ -36,14 +36,14 @@ fn shells(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream
         let mut dict = TaggedDictBuilder::new(&tag);
 
         if index == (*args.shell_manager.current_shell).load(Ordering::SeqCst) {
-            dict.insert(" ", "X".to_string());
+            dict.insert_untagged(" ", "X".to_string());
         } else {
-            dict.insert(" ", " ".to_string());
+            dict.insert_untagged(" ", " ".to_string());
         }
-        dict.insert("name", shell.name());
-        dict.insert("path", shell.path());
+        dict.insert_untagged("name", shell.name());
+        dict.insert_untagged("path", shell.path());
 
-        shells_out.push_back(dict.into_tagged_value());
+        shells_out.push_back(dict.into_value());
     }
 
     Ok(shells_out.to_output_stream())

src/commands/size.rs

@@ -30,22 +30,26 @@ impl WholeStreamCommand for Size {
 fn size(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let input = args.input;
     let tag = args.call_info.name_tag;
+    let name_span = tag.span;
+
     Ok(input
         .values
-        .map(move |v| match v.item {
-            Value::Primitive(Primitive::String(ref s)) => ReturnSuccess::value(count(s, v.tag())),
+        .map(move |v| match v.value {
+            UntaggedValue::Primitive(Primitive::String(ref s)) => {
+                ReturnSuccess::value(count(s, &v.tag))
+            }
             _ => Err(ShellError::labeled_error_with_secondary(
                 "Expected a string from pipeline",
                 "requires string input",
-                &tag,
+                name_span,
                 "value originates from here",
-                v.tag(),
+                v.tag.span,
             )),
         })
         .to_output_stream())
 }
 
-fn count(contents: &str, tag: impl Into<Tag>) -> Tagged<Value> {
+fn count(contents: &str, tag: impl Into<Tag>) -> Value {
     let mut lines: i64 = 0;
     let mut words: i64 = 0;
     let mut chars: i64 = 0;
@@ -72,11 +76,11 @@ fn count(contents: &str, tag: impl Into<Tag>) -> Tagged<Value> {
 
     let mut dict = TaggedDictBuilder::new(tag);
     //TODO: add back in name when we have it in the tag
-    //dict.insert("name", Value::string(name));
-    dict.insert("lines", Value::int(lines));
-    dict.insert("words", Value::int(words));
-    dict.insert("chars", Value::int(chars));
-    dict.insert("max length", Value::int(bytes));
+    //dict.insert("name", UntaggedValue::string(name));
+    dict.insert_untagged("lines", UntaggedValue::int(lines));
+    dict.insert_untagged("words", UntaggedValue::int(words));
+    dict.insert_untagged("chars", UntaggedValue::int(chars));
+    dict.insert_untagged("max length", UntaggedValue::int(bytes));
 
-    dict.into_tagged_value()
+    dict.into_value()
 }

src/commands/skip_while.rs

@@ -1,4 +1,5 @@
 use crate::commands::WholeStreamCommand;
+use crate::data::base::Block;
 use crate::errors::ShellError;
 use crate::prelude::*;
 use log::trace;
@@ -7,7 +8,7 @@ pub struct SkipWhile;
 
 #[derive(Deserialize)]
 pub struct SkipWhileArgs {
-    condition: value::Block,
+    condition: Block,
 }
 
 impl WholeStreamCommand for SkipWhile {

src/commands/sort_by.rs

@@ -1,6 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct SortBy;
 
@@ -38,10 +39,10 @@ fn sort_by(
     Ok(OutputStream::new(async_stream! {
         let mut vec = context.input.drain_vec().await;
 
-        let calc_key = |item: &Tagged<Value>| {
+        let calc_key = |item: &crate::data::base::Value| {
             rest.iter()
                 .map(|f| item.get_data_by_key(f.borrow_spanned()).map(|i| i.clone()))
-                .collect::<Vec<Option<Tagged<Value>>>>()
+                .collect::<Vec<Option<crate::data::base::Value>>>()
         };
         vec.sort_by_cached_key(calc_key);
 

src/commands/split_by.rs

@@ -1,7 +1,9 @@
 use crate::commands::WholeStreamCommand;
+use crate::data::base::UntaggedValue;
 use crate::data::TaggedDictBuilder;
 use crate::errors::ShellError;
 use crate::prelude::*;
+use nu_source::Tagged;
 
 pub struct SplitBy;
 
@@ -41,7 +43,7 @@ pub fn split_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         if values.len() > 1 || values.is_empty() {
             yield Err(ShellError::labeled_error(
@@ -62,22 +64,22 @@ pub fn split_by(
 
 pub fn split(
     column_name: &Tagged<String>,
-    value: &Tagged<Value>,
+    value: &Value,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let origin_tag = tag.into();
 
     let mut splits = indexmap::IndexMap::new();
 
     match value {
-        Tagged {
-            item: Value::Row(group_sets),
+        Value {
+            value: UntaggedValue::Row(group_sets),
             ..
         } => {
             for (group_key, group_value) in group_sets.entries.iter() {
                 match *group_value {
-                    Tagged {
-                        item: Value::Table(ref dataset),
+                    Value {
+                        value: UntaggedValue::Table(ref dataset),
                         ..
                     } => {
                         let group = crate::commands::group_by::group(
@@ -87,14 +89,14 @@ pub fn split(
                         )?;
 
                         match group {
-                            Tagged {
-                                item: Value::Row(o),
+                            Value {
+                                value: UntaggedValue::Row(o),
                                 ..
                             } => {
                                 for (split_label, subset) in o.entries.into_iter() {
                                     match subset {
-                                        Tagged {
-                                            item: Value::Table(subset),
+                                        Value {
+                                            value: UntaggedValue::Table(subset),
                                             tag,
                                         } => {
                                             let s = splits
@@ -102,7 +104,7 @@ pub fn split(
                                                 .or_insert(indexmap::IndexMap::new());
                                             s.insert(
                                                 group_key.clone(),
-                                                Value::table(&subset).tagged(tag),
+                                                UntaggedValue::table(&subset).into_value(tag),
                                             );
                                         }
                                         other => {
@@ -142,38 +144,38 @@ pub fn split(
     let mut out = TaggedDictBuilder::new(&origin_tag);
 
     for (k, v) in splits.into_iter() {
-        out.insert(k, Value::row(v));
+        out.insert_untagged(k, UntaggedValue::row(v));
     }
 
-    Ok(out.into_tagged_value())
+    Ok(out.into_value())
 }
 #[cfg(test)]
 mod tests {
 
     use crate::commands::group_by::group;
     use crate::commands::split_by::split;
-    use crate::data::meta::*;
-    use crate::Value;
+    use crate::data::base::{UntaggedValue, Value};
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn nu_releases_grouped_by_date() -> Tagged<Value> {
+    fn nu_releases_grouped_by_date() -> Value {
         let key = String::from("date").tagged_unknown();
         group(&key, nu_releases_commiters(), Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},
@@ -211,7 +213,7 @@ mod tests {
 
         assert_eq!(
             split(&for_key, &nu_releases_grouped_by_date(), Tag::unknown()).unwrap(),
-            Value::row(indexmap! {
+            UntaggedValue::row(indexmap! {
                 "EC".into() => row(indexmap! {
                     "August 23-2019".into() => table(&vec![
                         row(indexmap!{"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")})
@@ -245,7 +247,7 @@ mod tests {
                         row(indexmap!{"name".into() => string("YK"), "country".into() => string("US"), "date".into() => string("October 10-2019")})
                     ])
                 })
-            }).tagged_unknown()
+            }).into_untagged_value()
         );
     }
 
@@ -258,7 +260,7 @@ mod tests {
                     row(indexmap!{"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")})
             ]),
             "Sept 24-2019".into() =>  table(&vec![
-                    row(indexmap!{"name".into() => Value::string("JT").tagged(Tag::from(Span::new(5,10))), "date".into() => string("Sept 24-2019")})
+                    row(indexmap!{"name".into() => UntaggedValue::string("JT").into_value(Tag::from(Span::new(5,10))), "date".into() => string("Sept 24-2019")})
             ]),
             "October 10-2019".into() =>  table(&vec![
                     row(indexmap!{"name".into() => string("YK"), "country".into() => string("US"), "date".into() => string("October 10-2019")})

src/commands/split_column.rs

@@ -1,8 +1,9 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, TaggedDictBuilder, Value};
+use crate::data::{Primitive, TaggedDictBuilder};
 use crate::errors::ShellError;
 use crate::prelude::*;
 use log::trace;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 struct SplitColumnArgs {
@@ -51,10 +52,12 @@ fn split_column(
     }: SplitColumnArgs,
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
+    let name_span = name.span;
+
     Ok(input
         .values
-        .map(move |v| match v.item {
-            Value::Primitive(Primitive::String(ref s)) => {
+        .map(move |v| match v.value {
+            UntaggedValue::Primitive(Primitive::String(ref s)) => {
                 let splitter = separator.replace("\\n", "\n");
                 trace!("splitting with {:?}", splitter);
 
@@ -75,32 +78,38 @@ fn split_column(
                         gen_columns.push(format!("Column{}", i + 1));
                     }
 
-                    let mut dict = TaggedDictBuilder::new(v.tag());
+                    let mut dict = TaggedDictBuilder::new(&v.tag);
                     for (&k, v) in split_result.iter().zip(gen_columns.iter()) {
-                        dict.insert(v.clone(), Primitive::String(k.into()));
+                        dict.insert_untagged(v.clone(), Primitive::String(k.into()));
                     }
 
-                    ReturnSuccess::value(dict.into_tagged_value())
+                    ReturnSuccess::value(dict.into_value())
                 } else if split_result.len() == positional.len() {
-                    let mut dict = TaggedDictBuilder::new(v.tag());
+                    let mut dict = TaggedDictBuilder::new(&v.tag);
                     for (&k, v) in split_result.iter().zip(positional.iter()) {
-                        dict.insert(v, Value::Primitive(Primitive::String(k.into())));
+                        dict.insert_untagged(
+                            v,
+                            UntaggedValue::Primitive(Primitive::String(k.into())),
+                        );
                     }
-                    ReturnSuccess::value(dict.into_tagged_value())
+                    ReturnSuccess::value(dict.into_value())
                 } else {
-                    let mut dict = TaggedDictBuilder::new(v.tag());
+                    let mut dict = TaggedDictBuilder::new(&v.tag);
                     for (&k, v) in split_result.iter().zip(positional.iter()) {
-                        dict.insert(v, Value::Primitive(Primitive::String(k.into())));
+                        dict.insert_untagged(
+                            v,
+                            UntaggedValue::Primitive(Primitive::String(k.into())),
+                        );
                     }
-                    ReturnSuccess::value(dict.into_tagged_value())
+                    ReturnSuccess::value(dict.into_value())
                 }
             }
             _ => Err(ShellError::labeled_error_with_secondary(
                 "Expected a string from pipeline",
                 "requires string input",
-                &name,
+                name_span,
                 "value originates from here",
-                v.tag(),
+                v.tag.span,
             )),
         })
         .to_output_stream())

src/commands/split_row.rs

@@ -1,8 +1,9 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, Value};
+use crate::data::Primitive;
 use crate::errors::ShellError;
 use crate::prelude::*;
 use log::trace;
+use nu_source::Tagged;
 
 #[derive(Deserialize)]
 struct SplitRowArgs {
@@ -43,8 +44,8 @@ fn split_row(
 ) -> Result<OutputStream, ShellError> {
     let stream = input
         .values
-        .map(move |v| match v.item {
-            Value::Primitive(Primitive::String(ref s)) => {
+        .map(move |v| match v.value {
+            UntaggedValue::Primitive(Primitive::String(ref s)) => {
                 let splitter = separator.item.replace("\\n", "\n");
                 trace!("splitting with {:?}", splitter);
                 let split_result: Vec<_> = s.split(&splitter).filter(|s| s.trim() != "").collect();
@@ -54,7 +55,7 @@ fn split_row(
                 let mut result = VecDeque::new();
                 for s in split_result {
                     result.push_back(ReturnSuccess::value(
-                        Value::Primitive(Primitive::String(s.into())).tagged(v.tag()),
+                        UntaggedValue::Primitive(Primitive::String(s.into())).into_value(&v.tag),
                     ));
                 }
                 result
@@ -64,9 +65,9 @@ fn split_row(
                 result.push_back(Err(ShellError::labeled_error_with_secondary(
                     "Expected a string from pipeline",
                     "requires string input",
-                    &name,
+                    name.span,
                     "value originates from here",
-                    v.tag(),
+                    v.tag.span,
                 )));
                 result
             }

src/commands/t_sort_by.rs

@@ -3,6 +3,7 @@ use crate::data::{TaggedDictBuilder, TaggedListBuilder};
 use crate::errors::ShellError;
 use crate::prelude::*;
 use chrono::{DateTime, NaiveDate, Utc};
+use nu_source::Tagged;
 
 pub struct TSortBy;
 
@@ -57,7 +58,7 @@ fn t_sort_by(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     Ok(OutputStream::new(async_stream! {
-        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let values: Vec<Value> = input.values.collect().await;
 
         let column_grouped_by_name = if let Some(grouped_by) = group_by {
             Some(grouped_by.item().clone())
@@ -67,7 +68,7 @@ fn t_sort_by(
 
         if show_columns {
             for label in columns_sorted(column_grouped_by_name, &values[0], &name).into_iter() {
-                 yield ReturnSuccess::value(Value::string(label.item).tagged(label.tag));
+                 yield ReturnSuccess::value(UntaggedValue::string(label.item).into_value(label.tag));
             }
         } else {
             match t_sort(column_grouped_by_name, None, &values[0], name) {
@@ -80,41 +81,41 @@ fn t_sort_by(
 
 pub fn columns_sorted(
     _group_by_name: Option<String>,
-    value: &Tagged<Value>,
+    value: &Value,
     tag: impl Into<Tag>,
 ) -> Vec<Tagged<String>> {
     let origin_tag = tag.into();
 
     match value {
-        Tagged {
-            item: Value::Row(rows),
+        Value {
+            value: UntaggedValue::Row(rows),
             ..
         } => {
-            let mut keys: Vec<Tagged<Value>> =
-                rows.entries
-                    .keys()
-                    .map(|s| s.as_ref())
-                    .map(|k: &str| {
-                        let date = NaiveDate::parse_from_str(k, "%B %d-%Y");
+            let mut keys: Vec<Value> = rows
+                .entries
+                .keys()
+                .map(|s| s.as_ref())
+                .map(|k: &str| {
+                    let date = NaiveDate::parse_from_str(k, "%B %d-%Y");
 
-                        let date = match date {
-                            Ok(parsed) => Value::Primitive(Primitive::Date(
-                                DateTime::<Utc>::from_utc(parsed.and_hms(12, 34, 56), Utc),
-                            )),
-                            Err(_) => Value::string(k),
-                        };
+                    let date = match date {
+                        Ok(parsed) => UntaggedValue::Primitive(Primitive::Date(
+                            DateTime::<Utc>::from_utc(parsed.and_hms(12, 34, 56), Utc),
+                        )),
+                        Err(_) => UntaggedValue::string(k),
+                    };
 
-                        date.tagged_unknown()
-                    })
-                    .collect();
+                    date.into_untagged_value()
+                })
+                .collect();
 
             keys.sort();
 
             let keys: Vec<String> = keys
                 .into_iter()
                 .map(|k| match k {
-                    Tagged {
-                        item: Value::Primitive(Primitive::Date(d)),
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Date(d)),
                         ..
                     } => format!("{}", d.format("%B %d-%Y")),
                     _ => k.as_string().unwrap(),
@@ -130,9 +131,9 @@ pub fn columns_sorted(
 pub fn t_sort(
     group_by_name: Option<String>,
     split_by_name: Option<String>,
-    value: &Tagged<Value>,
+    value: &Value,
     tag: impl Into<Tag>,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let origin_tag = tag.into();
 
     match group_by_name {
@@ -143,12 +144,12 @@ pub fn t_sort(
             match split_by_name {
                 None => {
                     let mut dataset = TaggedDictBuilder::new(&origin_tag);
-                    dataset.insert_tagged("default", value.clone());
-                    let dataset = dataset.into_tagged_value();
+                    dataset.insert_value("default", value.clone());
+                    let dataset = dataset.into_value();
 
                     let split_labels: Vec<Tagged<String>> = match &dataset {
-                        Tagged {
-                            item: Value::Row(rows),
+                        Value {
+                            value: UntaggedValue::Row(rows),
                             ..
                         } => {
                             let mut keys: Vec<Tagged<String>> = rows
@@ -164,7 +165,7 @@ pub fn t_sort(
                         _ => vec![],
                     };
 
-                    let results: Vec<Vec<Tagged<Value>>> = split_labels
+                    let results: Vec<Vec<Value>> = split_labels
                         .iter()
                         .map(|split| {
                             let groups = dataset.get_data_by_key(split.borrow_spanned());
@@ -173,14 +174,14 @@ pub fn t_sort(
                                 .clone()
                                 .into_iter()
                                 .map(|label| match &groups {
-                                    Some(Tagged {
-                                        item: Value::Row(dict),
+                                    Some(Value {
+                                        value: UntaggedValue::Row(dict),
                                         ..
                                     }) => dict
                                         .get_data_by_key(label.borrow_spanned())
                                         .unwrap()
                                         .clone(),
-                                    _ => Value::Table(vec![]).tagged(&origin_tag),
+                                    _ => UntaggedValue::Table(vec![]).into_value(&origin_tag),
                                 })
                                 .collect()
                         })
@@ -189,15 +190,15 @@ pub fn t_sort(
                     let mut outer = TaggedListBuilder::new(&origin_tag);
 
                     for i in results {
-                        outer.insert_tagged(Value::Table(i).tagged(&origin_tag));
+                        outer.push_value(UntaggedValue::Table(i).into_value(&origin_tag));
                     }
 
-                    return Ok(Value::Table(outer.list).tagged(&origin_tag));
+                    return Ok(UntaggedValue::Table(outer.list).into_value(&origin_tag));
                 }
-                Some(_) => return Ok(Value::nothing().tagged(&origin_tag)),
+                Some(_) => return Ok(UntaggedValue::nothing().into_value(&origin_tag)),
             }
         }
-        None => return Ok(Value::nothing().tagged(&origin_tag)),
+        None => return Ok(UntaggedValue::nothing().into_value(&origin_tag)),
     }
 }
 #[cfg(test)]
@@ -205,28 +206,28 @@ mod tests {
 
     use crate::commands::group_by::group;
     use crate::commands::t_sort_by::{columns_sorted, t_sort};
-    use crate::data::meta::*;
-    use crate::Value;
+    use crate::data::base::{UntaggedValue, Value};
     use indexmap::IndexMap;
+    use nu_source::*;
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
-    fn nu_releases_grouped_by_date() -> Tagged<Value> {
+    fn nu_releases_grouped_by_date() -> Value {
         let key = String::from("date").tagged_unknown();
         group(&key, nu_releases_commiters(), Tag::unknown()).unwrap()
     }
 
-    fn nu_releases_commiters() -> Vec<Tagged<Value>> {
+    fn nu_releases_commiters() -> Vec<Value> {
         vec![
             row(
                 indexmap! {"name".into() => string("AR"), "country".into() => string("EC"), "date".into() => string("August 23-2019")},

src/commands/table.rs

@@ -37,7 +37,7 @@ fn table(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
     let stream = async_stream! {
         let host = args.host.clone();
         let start_number = match args.get("start_number") {
-            Some(Tagged { item: Value::Primitive(Primitive::Int(i)), .. }) => {
+            Some(Value { value: UntaggedValue::Primitive(Primitive::Int(i)), .. }) => {
                 i.to_usize().unwrap()
             }
             _ => {
@@ -45,7 +45,7 @@ fn table(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
             }
         };
 
-        let input: Vec<Tagged<Value>> = args.input.into_vec().await;
+        let input: Vec<Value> = args.input.into_vec().await;
         if input.len() > 0 {
             let mut host = host.lock().unwrap();
             let view = TableView::from_list(&input, start_number);
@@ -56,7 +56,7 @@ fn table(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
         }
         // Needed for async_stream to type check
         if false {
-            yield ReturnSuccess::value(Value::nothing().tagged_unknown());
+            yield ReturnSuccess::value(UntaggedValue::nothing().into_value(Tag::unknown()));
         }
     };
 

src/commands/tags.rs

@@ -1,5 +1,5 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{TaggedDictBuilder, Value};
+use crate::data::TaggedDictBuilder;
 use crate::errors::ShellError;
 use crate::prelude::*;
 
@@ -35,24 +35,24 @@ fn tags(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream,
             let mut tags = TaggedDictBuilder::new(v.tag());
             {
                 let anchor = v.anchor();
-                let span = v.tag().span;
+                let span = v.tag.span;
                 let mut dict = TaggedDictBuilder::new(v.tag());
-                dict.insert("start", Value::int(span.start() as i64));
-                dict.insert("end", Value::int(span.end() as i64));
-                tags.insert_tagged("span", dict.into_tagged_value());
+                dict.insert_untagged("start", UntaggedValue::int(span.start() as i64));
+                dict.insert_untagged("end", UntaggedValue::int(span.end() as i64));
+                tags.insert_value("span", dict.into_value());
 
                 match anchor {
                     Some(AnchorLocation::File(source)) => {
-                        tags.insert("anchor", Value::string(source));
+                        tags.insert_untagged("anchor", UntaggedValue::string(source));
                     }
                     Some(AnchorLocation::Url(source)) => {
-                        tags.insert("anchor", Value::string(source));
+                        tags.insert_untagged("anchor", UntaggedValue::string(source));
                     }
                     _ => {}
                 }
             }
 
-            tags.into_tagged_value()
+            tags.into_value()
         })
         .to_output_stream())
 }

src/commands/to_bson.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::data::{Dictionary, Primitive, Value};
 use crate::prelude::*;
-use crate::RawPathMember;
+use crate::UnspannedPathMember;
 use bson::{encode_document, oid::ObjectId, spec::BinarySubtype, Bson, Document};
 use std::convert::TryInto;
 
@@ -33,46 +33,48 @@ impl WholeStreamCommand for ToBSON {
     }
 }
 
-pub fn value_to_bson_value(v: &Tagged<Value>) -> Result<Bson, ShellError> {
-    Ok(match &v.item {
-        Value::Primitive(Primitive::Boolean(b)) => Bson::Boolean(*b),
+pub fn value_to_bson_value(v: &Value) -> Result<Bson, ShellError> {
+    Ok(match &v.value {
+        UntaggedValue::Primitive(Primitive::Boolean(b)) => Bson::Boolean(*b),
         // FIXME: What about really big decimals?
-        Value::Primitive(Primitive::Bytes(decimal)) => Bson::FloatingPoint(
+        UntaggedValue::Primitive(Primitive::Bytes(decimal)) => Bson::FloatingPoint(
             (decimal)
                 .to_f64()
                 .expect("Unimplemented BUG: What about big decimals?"),
         ),
-        Value::Primitive(Primitive::Duration(secs)) => Bson::I64(*secs as i64),
-        Value::Primitive(Primitive::Date(d)) => Bson::UtcDatetime(*d),
-        Value::Primitive(Primitive::EndOfStream) => Bson::Null,
-        Value::Primitive(Primitive::BeginningOfStream) => Bson::Null,
-        Value::Primitive(Primitive::Decimal(d)) => Bson::FloatingPoint(d.to_f64().unwrap()),
-        Value::Primitive(Primitive::Int(i)) => {
+        UntaggedValue::Primitive(Primitive::Duration(secs)) => Bson::I64(*secs as i64),
+        UntaggedValue::Primitive(Primitive::Date(d)) => Bson::UtcDatetime(*d),
+        UntaggedValue::Primitive(Primitive::EndOfStream) => Bson::Null,
+        UntaggedValue::Primitive(Primitive::BeginningOfStream) => Bson::Null,
+        UntaggedValue::Primitive(Primitive::Decimal(d)) => Bson::FloatingPoint(d.to_f64().unwrap()),
+        UntaggedValue::Primitive(Primitive::Int(i)) => {
             Bson::I64(i.tagged(&v.tag).coerce_into("converting to BSON")?)
         }
-        Value::Primitive(Primitive::Nothing) => Bson::Null,
-        Value::Primitive(Primitive::String(s)) => Bson::String(s.clone()),
-        Value::Primitive(Primitive::ColumnPath(path)) => Bson::Array(
+        UntaggedValue::Primitive(Primitive::Nothing) => Bson::Null,
+        UntaggedValue::Primitive(Primitive::String(s)) => Bson::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::ColumnPath(path)) => Bson::Array(
             path.iter()
-                .map(|x| match &x.item {
-                    RawPathMember::String(string) => Ok(Bson::String(string.clone())),
-                    RawPathMember::Int(int) => Ok(Bson::I64(
+                .map(|x| match &x.unspanned {
+                    UnspannedPathMember::String(string) => Ok(Bson::String(string.clone())),
+                    UnspannedPathMember::Int(int) => Ok(Bson::I64(
                         int.tagged(&v.tag).coerce_into("converting to BSON")?,
                     )),
                 })
                 .collect::<Result<Vec<Bson>, ShellError>>()?,
         ),
-        Value::Primitive(Primitive::Pattern(p)) => Bson::String(p.clone()),
-        Value::Primitive(Primitive::Path(s)) => Bson::String(s.display().to_string()),
-        Value::Table(l) => Bson::Array(
+        UntaggedValue::Primitive(Primitive::Pattern(p)) => Bson::String(p.clone()),
+        UntaggedValue::Primitive(Primitive::Path(s)) => Bson::String(s.display().to_string()),
+        UntaggedValue::Table(l) => Bson::Array(
             l.iter()
                 .map(|x| value_to_bson_value(x))
                 .collect::<Result<_, _>>()?,
         ),
-        Value::Block(_) => Bson::Null,
-        Value::Error(e) => return Err(e.clone()),
-        Value::Primitive(Primitive::Binary(b)) => Bson::Binary(BinarySubtype::Generic, b.clone()),
-        Value::Row(o) => object_value_to_bson(o)?,
+        UntaggedValue::Block(_) => Bson::Null,
+        UntaggedValue::Error(e) => return Err(e.clone()),
+        UntaggedValue::Primitive(Primitive::Binary(b)) => {
+            Bson::Binary(BinarySubtype::Generic, b.clone())
+        }
+        UntaggedValue::Row(o) => object_value_to_bson(o)?,
     })
 }
 
@@ -171,9 +173,9 @@ fn object_value_to_bson(o: &Dictionary) -> Result<Bson, ShellError> {
     }
 }
 
-fn get_binary_subtype<'a>(tagged_value: &'a Tagged<Value>) -> Result<BinarySubtype, ShellError> {
-    match tagged_value.item() {
-        Value::Primitive(Primitive::String(s)) => Ok(match s.as_ref() {
+fn get_binary_subtype<'a>(tagged_value: &'a Value) -> Result<BinarySubtype, ShellError> {
+    match &tagged_value.value {
+        UntaggedValue::Primitive(Primitive::String(s)) => Ok(match s.as_ref() {
             "generic" => BinarySubtype::Generic,
             "function" => BinarySubtype::Function,
             "binary_old" => BinarySubtype::BinaryOld,
@@ -182,7 +184,7 @@ fn get_binary_subtype<'a>(tagged_value: &'a Tagged<Value>) -> Result<BinarySubty
             "md5" => BinarySubtype::Md5,
             _ => unreachable!(),
         }),
-        Value::Primitive(Primitive::Int(i)) => Ok(BinarySubtype::UserDefined(
+        UntaggedValue::Primitive(Primitive::Int(i)) => Ok(BinarySubtype::UserDefined(
             i.tagged(&tagged_value.tag)
                 .coerce_into("converting to BSON binary subtype")?,
         )),
@@ -246,12 +248,14 @@ fn bson_value_to_bytes(bson: Bson, tag: Tag) -> Result<Vec<u8>, ShellError> {
 fn to_bson(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let name_tag = args.name_tag();
+    let name_span = name_tag.span;
+
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         let to_process_input = if input.len() > 1 {
             let tag = input[0].tag.clone();
-            vec![Tagged { item: Value::Table(input), tag } ]
+            vec![Value { value: UntaggedValue::Table(input), tag } ]
         } else if input.len() == 1 {
             input
         } else {
@@ -261,16 +265,18 @@ fn to_bson(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream
         for value in to_process_input {
             match value_to_bson_value(&value) {
                 Ok(bson_value) => {
+                    let value_span = value.tag.span;
+
                     match bson_value_to_bytes(bson_value, name_tag.clone()) {
                         Ok(x) => yield ReturnSuccess::value(
-                            Value::binary(x).tagged(&name_tag),
+                            UntaggedValue::binary(x).into_value(&name_tag),
                         ),
                         _ => yield Err(ShellError::labeled_error_with_secondary(
                             "Expected a table with BSON-compatible structure.tag() from pipeline",
                             "requires BSON-compatible input",
-                            &name_tag,
+                            name_span,
                             "originates from here".to_string(),
-                            value.tag(),
+                            value_span,
                         )),
                     }
                 }

src/commands/to_csv.rs

@@ -8,7 +8,7 @@ pub struct ToCSV;
 #[derive(Deserialize)]
 pub struct ToCSVArgs {
     headerless: bool,
-    separator: Option<Tagged<Value>>,
+    separator: Option<Value>,
 }
 
 impl WholeStreamCommand for ToCSV {
@@ -44,8 +44,8 @@ fn to_csv(
     runnable_context: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let sep = match separator {
-        Some(Tagged {
-            item: Value::Primitive(Primitive::String(s)),
+        Some(Value {
+            value: UntaggedValue::Primitive(Primitive::String(s)),
             tag,
             ..
         }) => {

src/commands/to_delimited_data.rs

@@ -2,15 +2,16 @@ use crate::data::{Primitive, Value};
 use crate::prelude::*;
 use csv::WriterBuilder;
 use indexmap::{indexset, IndexSet};
+use nu_source::Spanned;
 
 fn from_value_to_delimited_string(
-    tagged_value: &Tagged<Value>,
+    tagged_value: &Value,
     separator: char,
 ) -> Result<String, ShellError> {
-    let v = &tagged_value.item;
+    let v = &tagged_value.value;
 
     match v {
-        Value::Row(o) => {
+        UntaggedValue::Row(o) => {
             let mut wtr = WriterBuilder::new()
                 .delimiter(separator as u8)
                 .from_writer(vec![]);
@@ -41,7 +42,7 @@ fn from_value_to_delimited_string(
                 )
             })?);
         }
-        Value::Table(list) => {
+        UntaggedValue::Table(list) => {
             let mut wtr = WriterBuilder::new()
                 .delimiter(separator as u8)
                 .from_writer(vec![]);
@@ -54,7 +55,7 @@ fn from_value_to_delimited_string(
             for l in list {
                 let mut row = vec![];
                 for desc in &merged_descriptors {
-                    match l.item.get_data_by_key(desc.borrow_spanned()) {
+                    match l.get_data_by_key(desc.borrow_spanned()) {
                         Some(s) => {
                             row.push(to_string_tagged_value(&s)?);
                         }
@@ -85,40 +86,56 @@ fn from_value_to_delimited_string(
     }
 }
 
-// NOTE: could this be useful more widely and implemented on Tagged<Value> ?
-pub fn clone_tagged_value(v: &Tagged<Value>) -> Tagged<Value> {
-    match &v.item {
-        Value::Primitive(Primitive::String(s)) => Value::Primitive(Primitive::String(s.clone())),
-        Value::Primitive(Primitive::Nothing) => Value::Primitive(Primitive::Nothing),
-        Value::Primitive(Primitive::Boolean(b)) => Value::Primitive(Primitive::Boolean(b.clone())),
-        Value::Primitive(Primitive::Decimal(f)) => Value::Primitive(Primitive::Decimal(f.clone())),
-        Value::Primitive(Primitive::Int(i)) => Value::Primitive(Primitive::Int(i.clone())),
-        Value::Primitive(Primitive::Path(x)) => Value::Primitive(Primitive::Path(x.clone())),
-        Value::Primitive(Primitive::Bytes(b)) => Value::Primitive(Primitive::Bytes(b.clone())),
-        Value::Primitive(Primitive::Date(d)) => Value::Primitive(Primitive::Date(d.clone())),
-        Value::Row(o) => Value::Row(o.clone()),
-        Value::Table(l) => Value::Table(l.clone()),
-        Value::Block(_) => Value::Primitive(Primitive::Nothing),
-        _ => Value::Primitive(Primitive::Nothing),
+// NOTE: could this be useful more widely and implemented on Value ?
+pub fn clone_tagged_value(v: &Value) -> Value {
+    match &v.value {
+        UntaggedValue::Primitive(Primitive::String(s)) => {
+            UntaggedValue::Primitive(Primitive::String(s.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Nothing) => {
+            UntaggedValue::Primitive(Primitive::Nothing)
+        }
+        UntaggedValue::Primitive(Primitive::Boolean(b)) => {
+            UntaggedValue::Primitive(Primitive::Boolean(b.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Decimal(f)) => {
+            UntaggedValue::Primitive(Primitive::Decimal(f.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Int(i)) => {
+            UntaggedValue::Primitive(Primitive::Int(i.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Path(x)) => {
+            UntaggedValue::Primitive(Primitive::Path(x.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Bytes(b)) => {
+            UntaggedValue::Primitive(Primitive::Bytes(b.clone()))
+        }
+        UntaggedValue::Primitive(Primitive::Date(d)) => {
+            UntaggedValue::Primitive(Primitive::Date(d.clone()))
+        }
+        UntaggedValue::Row(o) => UntaggedValue::Row(o.clone()),
+        UntaggedValue::Table(l) => UntaggedValue::Table(l.clone()),
+        UntaggedValue::Block(_) => UntaggedValue::Primitive(Primitive::Nothing),
+        _ => UntaggedValue::Primitive(Primitive::Nothing),
     }
-    .tagged(v.tag.clone())
+    .into_value(v.tag.clone())
 }
 
-// NOTE: could this be useful more widely and implemented on Tagged<Value> ?
-fn to_string_tagged_value(v: &Tagged<Value>) -> Result<String, ShellError> {
-    match &v.item {
-        Value::Primitive(Primitive::Date(d)) => Ok(d.to_string()),
-        Value::Primitive(Primitive::Bytes(b)) => {
+// NOTE: could this be useful more widely and implemented on Value ?
+fn to_string_tagged_value(v: &Value) -> Result<String, ShellError> {
+    match &v.value {
+        UntaggedValue::Primitive(Primitive::Date(d)) => Ok(d.to_string()),
+        UntaggedValue::Primitive(Primitive::Bytes(b)) => {
             let tmp = format!("{}", b);
             Ok(tmp)
         }
-        Value::Primitive(Primitive::Boolean(_)) => Ok(v.as_string()?),
-        Value::Primitive(Primitive::Decimal(_)) => Ok(v.as_string()?),
-        Value::Primitive(Primitive::Int(_)) => Ok(v.as_string()?),
-        Value::Primitive(Primitive::Path(_)) => Ok(v.as_string()?),
-        Value::Table(_) => return Ok(String::from("[Table]")),
-        Value::Row(_) => return Ok(String::from("[Row]")),
-        Value::Primitive(Primitive::String(s)) => return Ok(s.to_string()),
+        UntaggedValue::Primitive(Primitive::Boolean(_)) => Ok(v.as_string()?),
+        UntaggedValue::Primitive(Primitive::Decimal(_)) => Ok(v.as_string()?),
+        UntaggedValue::Primitive(Primitive::Int(_)) => Ok(v.as_string()?),
+        UntaggedValue::Primitive(Primitive::Path(_)) => Ok(v.as_string()?),
+        UntaggedValue::Table(_) => return Ok(String::from("[Table]")),
+        UntaggedValue::Row(_) => return Ok(String::from("[Row]")),
+        UntaggedValue::Primitive(Primitive::String(s)) => return Ok(s.to_string()),
         _ => {
             return Err(ShellError::labeled_error(
                 "Unexpected value",
@@ -129,7 +146,7 @@ fn to_string_tagged_value(v: &Tagged<Value>) -> Result<String, ShellError> {
     }
 }
 
-fn merge_descriptors(values: &[Tagged<Value>]) -> Vec<Spanned<String>> {
+fn merge_descriptors(values: &[Value]) -> Vec<Spanned<String>> {
     let mut ret: Vec<Spanned<String>> = vec![];
     let mut seen: IndexSet<String> = indexset! {};
     for value in values {
@@ -150,13 +167,14 @@ pub fn to_delimited_data(
     RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
     let name_tag = name;
+    let name_span = name_tag.span;
 
     let stream = async_stream! {
-         let input: Vec<Tagged<Value>> = input.values.collect().await;
+         let input: Vec<Value> = input.values.collect().await;
 
          let to_process_input = if input.len() > 1 {
              let tag = input[0].tag.clone();
-             vec![Tagged { item: Value::Table(input), tag } ]
+             vec![Value { value: UntaggedValue::Table(input), tag } ]
          } else if input.len() == 1 {
              input
          } else {
@@ -171,7 +189,7 @@ pub fn to_delimited_data(
                      } else {
                          x
                      };
-                     yield ReturnSuccess::value(Value::Primitive(Primitive::String(converted)).tagged(&name_tag))
+                     yield ReturnSuccess::value(UntaggedValue::Primitive(Primitive::String(converted)).into_value(&name_tag))
                  }
                  _ => {
                      let expected = format!("Expected a table with {}-compatible structure.tag() from pipeline", format_name);
@@ -179,9 +197,9 @@ pub fn to_delimited_data(
                      yield Err(ShellError::labeled_error_with_secondary(
                          expected,
                          requires,
-                         &name_tag,
+                         name_span,
                          "originates from here".to_string(),
-                         value.tag(),
+                         value.tag.span,
                      ))
                  }
              }

src/commands/to_json.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Primitive, Value};
+use crate::data::base::{Primitive, UntaggedValue, Value};
 use crate::prelude::*;
-use crate::RawPathMember;
+use crate::UnspannedPathMember;
 
 pub struct ToJSON;
 
@@ -27,35 +27,40 @@ impl WholeStreamCommand for ToJSON {
     }
 }
 
-pub fn value_to_json_value(v: &Tagged<Value>) -> Result<serde_json::Value, ShellError> {
-    Ok(match v.item() {
-        Value::Primitive(Primitive::Boolean(b)) => serde_json::Value::Bool(*b),
-        Value::Primitive(Primitive::Bytes(b)) => serde_json::Value::Number(
+pub fn value_to_json_value(v: &Value) -> Result<serde_json::Value, ShellError> {
+    Ok(match &v.value {
+        UntaggedValue::Primitive(Primitive::Boolean(b)) => serde_json::Value::Bool(*b),
+        UntaggedValue::Primitive(Primitive::Bytes(b)) => serde_json::Value::Number(
             serde_json::Number::from(b.to_u64().expect("What about really big numbers")),
         ),
-        Value::Primitive(Primitive::Duration(secs)) => {
+        UntaggedValue::Primitive(Primitive::Duration(secs)) => {
             serde_json::Value::Number(serde_json::Number::from(*secs))
         }
-        Value::Primitive(Primitive::Date(d)) => serde_json::Value::String(d.to_string()),
-        Value::Primitive(Primitive::EndOfStream) => serde_json::Value::Null,
-        Value::Primitive(Primitive::BeginningOfStream) => serde_json::Value::Null,
-        Value::Primitive(Primitive::Decimal(f)) => serde_json::Value::Number(
+        UntaggedValue::Primitive(Primitive::Date(d)) => serde_json::Value::String(d.to_string()),
+        UntaggedValue::Primitive(Primitive::EndOfStream) => serde_json::Value::Null,
+        UntaggedValue::Primitive(Primitive::BeginningOfStream) => serde_json::Value::Null,
+        UntaggedValue::Primitive(Primitive::Decimal(f)) => serde_json::Value::Number(
             serde_json::Number::from_f64(
                 f.to_f64().expect("TODO: What about really big decimals?"),
             )
             .unwrap(),
         ),
-        Value::Primitive(Primitive::Int(i)) => serde_json::Value::Number(serde_json::Number::from(
-            CoerceInto::<i64>::coerce_into(i.tagged(&v.tag), "converting to JSON number")?,
-        )),
-        Value::Primitive(Primitive::Nothing) => serde_json::Value::Null,
-        Value::Primitive(Primitive::Pattern(s)) => serde_json::Value::String(s.clone()),
-        Value::Primitive(Primitive::String(s)) => serde_json::Value::String(s.clone()),
-        Value::Primitive(Primitive::ColumnPath(path)) => serde_json::Value::Array(
+        UntaggedValue::Primitive(Primitive::Int(i)) => {
+            serde_json::Value::Number(serde_json::Number::from(CoerceInto::<i64>::coerce_into(
+                i.tagged(&v.tag),
+                "converting to JSON number",
+            )?))
+        }
+        UntaggedValue::Primitive(Primitive::Nothing) => serde_json::Value::Null,
+        UntaggedValue::Primitive(Primitive::Pattern(s)) => serde_json::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::String(s)) => serde_json::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::ColumnPath(path)) => serde_json::Value::Array(
             path.iter()
-                .map(|x| match &x.item {
-                    RawPathMember::String(string) => Ok(serde_json::Value::String(string.clone())),
-                    RawPathMember::Int(int) => Ok(serde_json::Value::Number(
+                .map(|x| match &x.unspanned {
+                    UnspannedPathMember::String(string) => {
+                        Ok(serde_json::Value::String(string.clone()))
+                    }
+                    UnspannedPathMember::Int(int) => Ok(serde_json::Value::Number(
                         serde_json::Number::from(CoerceInto::<i64>::coerce_into(
                             int.tagged(&v.tag),
                             "converting to JSON number",
@@ -64,19 +69,21 @@ pub fn value_to_json_value(v: &Tagged<Value>) -> Result<serde_json::Value, Shell
                 })
                 .collect::<Result<Vec<serde_json::Value>, ShellError>>()?,
         ),
-        Value::Primitive(Primitive::Path(s)) => serde_json::Value::String(s.display().to_string()),
+        UntaggedValue::Primitive(Primitive::Path(s)) => {
+            serde_json::Value::String(s.display().to_string())
+        }
 
-        Value::Table(l) => serde_json::Value::Array(json_list(l)?),
-        Value::Error(e) => return Err(e.clone()),
-        Value::Block(_) => serde_json::Value::Null,
-        Value::Primitive(Primitive::Binary(b)) => serde_json::Value::Array(
+        UntaggedValue::Table(l) => serde_json::Value::Array(json_list(l)?),
+        UntaggedValue::Error(e) => return Err(e.clone()),
+        UntaggedValue::Block(_) => serde_json::Value::Null,
+        UntaggedValue::Primitive(Primitive::Binary(b)) => serde_json::Value::Array(
             b.iter()
                 .map(|x| {
                     serde_json::Value::Number(serde_json::Number::from_f64(*x as f64).unwrap())
                 })
                 .collect(),
         ),
-        Value::Row(o) => {
+        UntaggedValue::Row(o) => {
             let mut m = serde_json::Map::new();
             for (k, v) in o.entries.iter() {
                 m.insert(k.clone(), value_to_json_value(v)?);
@@ -86,7 +93,7 @@ pub fn value_to_json_value(v: &Tagged<Value>) -> Result<serde_json::Value, Shell
     })
 }
 
-fn json_list(input: &Vec<Tagged<Value>>) -> Result<Vec<serde_json::Value>, ShellError> {
+fn json_list(input: &Vec<Value>) -> Result<Vec<serde_json::Value>, ShellError> {
     let mut out = vec![];
 
     for value in input {
@@ -99,12 +106,13 @@ fn json_list(input: &Vec<Tagged<Value>>) -> Result<Vec<serde_json::Value>, Shell
 fn to_json(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let name_tag = args.name_tag();
+    let name_span = name_tag.span;
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         let to_process_input = if input.len() > 1 {
             let tag = input[0].tag.clone();
-            vec![Tagged { item: Value::Table(input), tag } ]
+            vec![Value { value: UntaggedValue::Table(input), tag } ]
         } else if input.len() == 1 {
             input
         } else {
@@ -114,16 +122,18 @@ fn to_json(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream
         for value in to_process_input {
             match value_to_json_value(&value) {
                 Ok(json_value) => {
+                    let value_span = value.tag.span;
+
                     match serde_json::to_string(&json_value) {
                         Ok(x) => yield ReturnSuccess::value(
-                            Value::Primitive(Primitive::String(x)).tagged(&name_tag),
+                            UntaggedValue::Primitive(Primitive::String(x)).into_value(&name_tag),
                         ),
                         _ => yield Err(ShellError::labeled_error_with_secondary(
                             "Expected a table with JSON-compatible structure.tag() from pipeline",
                             "requires JSON-compatible input",
-                            &name_tag,
+                            name_span,
                             "originates from here".to_string(),
-                            value.tag(),
+                            value_span,
                         )),
                     }
                 }

src/commands/to_sqlite.rs

@@ -69,9 +69,9 @@ fn comma_concat(acc: String, current: String) -> String {
     }
 }
 
-fn get_columns(rows: &Vec<Tagged<Value>>) -> Result<String, std::io::Error> {
-    match &rows[0].item {
-        Value::Row(d) => Ok(d
+fn get_columns(rows: &Vec<Value>) -> Result<String, std::io::Error> {
+    match &rows[0].value {
+        UntaggedValue::Row(d) => Ok(d
             .entries
             .iter()
             .map(|(k, _v)| k.clone())
@@ -84,8 +84,8 @@ fn get_columns(rows: &Vec<Tagged<Value>>) -> Result<String, std::io::Error> {
 }
 
 fn nu_value_to_sqlite_string(v: Value) -> String {
-    match v {
-        Value::Primitive(p) => match p {
+    match &v.value {
+        UntaggedValue::Primitive(p) => match p {
             Primitive::Nothing => "NULL".into(),
             Primitive::Int(i) => format!("{}", i),
             Primitive::Duration(u) => format!("{}", u),
@@ -106,15 +106,15 @@ fn nu_value_to_sqlite_string(v: Value) -> String {
     }
 }
 
-fn get_insert_values(rows: Vec<Tagged<Value>>) -> Result<String, std::io::Error> {
+fn get_insert_values(rows: Vec<Value>) -> Result<String, std::io::Error> {
     let values: Result<Vec<_>, _> = rows
         .into_iter()
-        .map(|value| match value.item {
-            Value::Row(d) => Ok(format!(
+        .map(|value| match value.value {
+            UntaggedValue::Row(d) => Ok(format!(
                 "({})",
                 d.entries
                     .iter()
-                    .map(|(_k, v)| nu_value_to_sqlite_string(v.item.clone()))
+                    .map(|(_k, v)| nu_value_to_sqlite_string(v.clone()))
                     .fold("".to_string(), comma_concat)
             )),
             _ => Err(std::io::Error::new(
@@ -129,8 +129,8 @@ fn get_insert_values(rows: Vec<Tagged<Value>>) -> Result<String, std::io::Error>
 
 fn generate_statements(table: Dictionary) -> Result<(String, String), std::io::Error> {
     let table_name = match table.entries.get("table_name") {
-        Some(Tagged {
-            item: Value::Primitive(Primitive::String(table_name)),
+        Some(Value {
+            value: UntaggedValue::Primitive(Primitive::String(table_name)),
             ..
         }) => table_name,
         _ => {
@@ -141,8 +141,8 @@ fn generate_statements(table: Dictionary) -> Result<(String, String), std::io::E
         }
     };
     let (columns, insert_values) = match table.entries.get("table_values") {
-        Some(Tagged {
-            item: Value::Table(l),
+        Some(Value {
+            value: UntaggedValue::Table(l),
             ..
         }) => (get_columns(l), get_insert_values(l.to_vec())),
         _ => {
@@ -157,9 +157,7 @@ fn generate_statements(table: Dictionary) -> Result<(String, String), std::io::E
     Ok((create, insert))
 }
 
-fn sqlite_input_stream_to_bytes(
-    values: Vec<Tagged<Value>>,
-) -> Result<Tagged<Value>, std::io::Error> {
+fn sqlite_input_stream_to_bytes(values: Vec<Value>) -> Result<Value, std::io::Error> {
     // FIXME: should probably write a sqlite virtual filesystem
     // that will allow us to use bytes as a file to avoid this
     // write out, but this will require C code. Might be
@@ -171,8 +169,8 @@ fn sqlite_input_stream_to_bytes(
     };
     let tag = values[0].tag.clone();
     for value in values.into_iter() {
-        match value.item() {
-            Value::Row(d) => {
+        match &value.value {
+            UntaggedValue::Row(d) => {
                 let (create, insert) = generate_statements(d.to_owned())?;
                 match conn
                     .execute(&create, NO_PARAMS)
@@ -197,14 +195,14 @@ fn sqlite_input_stream_to_bytes(
     }
     let mut out = Vec::new();
     tempfile.read_to_end(&mut out)?;
-    Ok(Value::binary(out).tagged(tag))
+    Ok(UntaggedValue::binary(out).into_value(tag))
 }
 
 fn to_sqlite(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let name_tag = args.name_tag();
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         match sqlite_input_stream_to_bytes(input) {
             Ok(out) => yield ReturnSuccess::value(out),

src/commands/to_toml.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::data::{Primitive, Value};
 use crate::prelude::*;
-use crate::RawPathMember;
+use crate::UnspannedPathMember;
 
 pub struct ToTOML;
 
@@ -27,33 +27,37 @@ impl WholeStreamCommand for ToTOML {
     }
 }
 
-pub fn value_to_toml_value(v: &Tagged<Value>) -> Result<toml::Value, ShellError> {
-    Ok(match v.item() {
-        Value::Primitive(Primitive::Boolean(b)) => toml::Value::Boolean(*b),
-        Value::Primitive(Primitive::Bytes(b)) => toml::Value::Integer(*b as i64),
-        Value::Primitive(Primitive::Duration(d)) => toml::Value::Integer(*d as i64),
-        Value::Primitive(Primitive::Date(d)) => toml::Value::String(d.to_string()),
-        Value::Primitive(Primitive::EndOfStream) => {
+pub fn value_to_toml_value(v: &Value) -> Result<toml::Value, ShellError> {
+    Ok(match &v.value {
+        UntaggedValue::Primitive(Primitive::Boolean(b)) => toml::Value::Boolean(*b),
+        UntaggedValue::Primitive(Primitive::Bytes(b)) => toml::Value::Integer(*b as i64),
+        UntaggedValue::Primitive(Primitive::Duration(d)) => toml::Value::Integer(*d as i64),
+        UntaggedValue::Primitive(Primitive::Date(d)) => toml::Value::String(d.to_string()),
+        UntaggedValue::Primitive(Primitive::EndOfStream) => {
             toml::Value::String("<End of Stream>".to_string())
         }
-        Value::Primitive(Primitive::BeginningOfStream) => {
+        UntaggedValue::Primitive(Primitive::BeginningOfStream) => {
             toml::Value::String("<Beginning of Stream>".to_string())
         }
-        Value::Primitive(Primitive::Decimal(f)) => {
+        UntaggedValue::Primitive(Primitive::Decimal(f)) => {
             toml::Value::Float(f.tagged(&v.tag).coerce_into("converting to TOML float")?)
         }
-        Value::Primitive(Primitive::Int(i)) => {
+        UntaggedValue::Primitive(Primitive::Int(i)) => {
             toml::Value::Integer(i.tagged(&v.tag).coerce_into("converting to TOML integer")?)
         }
-        Value::Primitive(Primitive::Nothing) => toml::Value::String("<Nothing>".to_string()),
-        Value::Primitive(Primitive::Pattern(s)) => toml::Value::String(s.clone()),
-        Value::Primitive(Primitive::String(s)) => toml::Value::String(s.clone()),
-        Value::Primitive(Primitive::Path(s)) => toml::Value::String(s.display().to_string()),
-        Value::Primitive(Primitive::ColumnPath(path)) => toml::Value::Array(
+        UntaggedValue::Primitive(Primitive::Nothing) => {
+            toml::Value::String("<Nothing>".to_string())
+        }
+        UntaggedValue::Primitive(Primitive::Pattern(s)) => toml::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::String(s)) => toml::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::Path(s)) => {
+            toml::Value::String(s.display().to_string())
+        }
+        UntaggedValue::Primitive(Primitive::ColumnPath(path)) => toml::Value::Array(
             path.iter()
-                .map(|x| match &x.item {
-                    RawPathMember::String(string) => Ok(toml::Value::String(string.clone())),
-                    RawPathMember::Int(int) => Ok(toml::Value::Integer(
+                .map(|x| match &x.unspanned {
+                    UnspannedPathMember::String(string) => Ok(toml::Value::String(string.clone())),
+                    UnspannedPathMember::Int(int) => Ok(toml::Value::Integer(
                         int.tagged(&v.tag)
                             .coerce_into("converting to TOML integer")?,
                     )),
@@ -61,13 +65,13 @@ pub fn value_to_toml_value(v: &Tagged<Value>) -> Result<toml::Value, ShellError>
                 .collect::<Result<Vec<toml::Value>, ShellError>>()?,
         ),
 
-        Value::Table(l) => toml::Value::Array(collect_values(l)?),
-        Value::Error(e) => return Err(e.clone()),
-        Value::Block(_) => toml::Value::String("<Block>".to_string()),
-        Value::Primitive(Primitive::Binary(b)) => {
+        UntaggedValue::Table(l) => toml::Value::Array(collect_values(l)?),
+        UntaggedValue::Error(e) => return Err(e.clone()),
+        UntaggedValue::Block(_) => toml::Value::String("<Block>".to_string()),
+        UntaggedValue::Primitive(Primitive::Binary(b)) => {
             toml::Value::Array(b.iter().map(|x| toml::Value::Integer(*x as i64)).collect())
         }
-        Value::Row(o) => {
+        UntaggedValue::Row(o) => {
             let mut m = toml::map::Map::new();
             for (k, v) in o.entries.iter() {
                 m.insert(k.clone(), value_to_toml_value(v)?);
@@ -77,7 +81,7 @@ pub fn value_to_toml_value(v: &Tagged<Value>) -> Result<toml::Value, ShellError>
     })
 }
 
-fn collect_values(input: &Vec<Tagged<Value>>) -> Result<Vec<toml::Value>, ShellError> {
+fn collect_values(input: &Vec<Value>) -> Result<Vec<toml::Value>, ShellError> {
     let mut out = vec![];
 
     for value in input {
@@ -90,12 +94,13 @@ fn collect_values(input: &Vec<Tagged<Value>>) -> Result<Vec<toml::Value>, ShellE
 fn to_toml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let name_tag = args.name_tag();
+    let name_span = name_tag.span;
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         let to_process_input = if input.len() > 1 {
             let tag = input[0].tag.clone();
-            vec![Tagged { item: Value::Table(input), tag } ]
+            vec![Value { value: UntaggedValue::Table(input), tag } ]
         } else if input.len() == 1 {
             input
         } else {
@@ -103,18 +108,19 @@ fn to_toml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream
         };
 
         for value in to_process_input {
+            let value_span = value.tag.span;
             match value_to_toml_value(&value) {
                 Ok(toml_value) => {
                     match toml::to_string(&toml_value) {
                         Ok(x) => yield ReturnSuccess::value(
-                            Value::Primitive(Primitive::String(x)).tagged(&name_tag),
+                            UntaggedValue::Primitive(Primitive::String(x)).into_value(&name_tag),
                         ),
                         _ => yield Err(ShellError::labeled_error_with_secondary(
                             "Expected a table with TOML-compatible structure.tag() from pipeline",
                             "requires TOML-compatible input",
-                            &name_tag,
+                            name_span,
                             "originates from here".to_string(),
-                            value.tag(),
+                            value_span,
                         )),
                     }
                 }

src/commands/to_url.rs

@@ -32,11 +32,11 @@ fn to_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
     let input = args.input;
 
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = input.values.collect().await;
+        let input: Vec<Value> = input.values.collect().await;
 
         for value in input {
             match value {
-                Tagged { item: Value::Row(row), .. } => {
+                Value { value: UntaggedValue::Row(row), .. } => {
                     let mut row_vec = vec![];
                     for (k,v) in row.entries {
                         match v.as_string() {
@@ -57,7 +57,7 @@ fn to_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
 
                     match serde_urlencoded::to_string(row_vec) {
                         Ok(s) => {
-                            yield ReturnSuccess::value(Value::string(s).tagged(&tag));
+                            yield ReturnSuccess::value(UntaggedValue::string(s).into_value(&tag));
                         }
                         _ => {
                             yield Err(ShellError::labeled_error(
@@ -68,13 +68,13 @@ fn to_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
                         }
                     }
                 }
-                Tagged { tag: value_tag, .. } => {
+                Value { tag: value_tag, .. } => {
                     yield Err(ShellError::labeled_error_with_secondary(
                         "Expected a table from pipeline",
                         "requires table input",
                         &tag,
                         "value originates from here",
-                        value_tag,
+                        value_tag.span,
                     ))
                 }
             }

src/commands/to_yaml.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::data::{Primitive, Value};
 use crate::prelude::*;
-use crate::RawPathMember;
+use crate::UnspannedPathMember;
 
 pub struct ToYAML;
 
@@ -27,36 +27,39 @@ impl WholeStreamCommand for ToYAML {
     }
 }
 
-pub fn value_to_yaml_value(v: &Tagged<Value>) -> Result<serde_yaml::Value, ShellError> {
-    Ok(match v.item() {
-        Value::Primitive(Primitive::Boolean(b)) => serde_yaml::Value::Bool(*b),
-        Value::Primitive(Primitive::Bytes(b)) => {
+pub fn value_to_yaml_value(v: &Value) -> Result<serde_yaml::Value, ShellError> {
+    Ok(match &v.value {
+        UntaggedValue::Primitive(Primitive::Boolean(b)) => serde_yaml::Value::Bool(*b),
+        UntaggedValue::Primitive(Primitive::Bytes(b)) => {
             serde_yaml::Value::Number(serde_yaml::Number::from(b.to_f64().unwrap()))
         }
-        Value::Primitive(Primitive::Duration(secs)) => {
+        UntaggedValue::Primitive(Primitive::Duration(secs)) => {
             serde_yaml::Value::Number(serde_yaml::Number::from(secs.to_f64().unwrap()))
         }
-        Value::Primitive(Primitive::Date(d)) => serde_yaml::Value::String(d.to_string()),
-        Value::Primitive(Primitive::EndOfStream) => serde_yaml::Value::Null,
-        Value::Primitive(Primitive::BeginningOfStream) => serde_yaml::Value::Null,
-        Value::Primitive(Primitive::Decimal(f)) => {
+        UntaggedValue::Primitive(Primitive::Date(d)) => serde_yaml::Value::String(d.to_string()),
+        UntaggedValue::Primitive(Primitive::EndOfStream) => serde_yaml::Value::Null,
+        UntaggedValue::Primitive(Primitive::BeginningOfStream) => serde_yaml::Value::Null,
+        UntaggedValue::Primitive(Primitive::Decimal(f)) => {
             serde_yaml::Value::Number(serde_yaml::Number::from(f.to_f64().unwrap()))
         }
-        Value::Primitive(Primitive::Int(i)) => serde_yaml::Value::Number(serde_yaml::Number::from(
-            CoerceInto::<i64>::coerce_into(i.tagged(&v.tag), "converting to YAML number")?,
-        )),
-        Value::Primitive(Primitive::Nothing) => serde_yaml::Value::Null,
-        Value::Primitive(Primitive::Pattern(s)) => serde_yaml::Value::String(s.clone()),
-        Value::Primitive(Primitive::String(s)) => serde_yaml::Value::String(s.clone()),
-        Value::Primitive(Primitive::ColumnPath(path)) => {
+        UntaggedValue::Primitive(Primitive::Int(i)) => {
+            serde_yaml::Value::Number(serde_yaml::Number::from(CoerceInto::<i64>::coerce_into(
+                i.tagged(&v.tag),
+                "converting to YAML number",
+            )?))
+        }
+        UntaggedValue::Primitive(Primitive::Nothing) => serde_yaml::Value::Null,
+        UntaggedValue::Primitive(Primitive::Pattern(s)) => serde_yaml::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::String(s)) => serde_yaml::Value::String(s.clone()),
+        UntaggedValue::Primitive(Primitive::ColumnPath(path)) => {
             let mut out = vec![];
 
             for member in path.iter() {
-                match &member.item {
-                    RawPathMember::String(string) => {
+                match &member.unspanned {
+                    UnspannedPathMember::String(string) => {
                         out.push(serde_yaml::Value::String(string.clone()))
                     }
-                    RawPathMember::Int(int) => out.push(serde_yaml::Value::Number(
+                    UnspannedPathMember::Int(int) => out.push(serde_yaml::Value::Number(
                         serde_yaml::Number::from(CoerceInto::<i64>::coerce_into(
                             int.tagged(&member.span),
                             "converting to YAML number",
@@ -67,9 +70,11 @@ pub fn value_to_yaml_value(v: &Tagged<Value>) -> Result<serde_yaml::Value, Shell
 
             serde_yaml::Value::Sequence(out)
         }
-        Value::Primitive(Primitive::Path(s)) => serde_yaml::Value::String(s.display().to_string()),
+        UntaggedValue::Primitive(Primitive::Path(s)) => {
+            serde_yaml::Value::String(s.display().to_string())
+        }
 
-        Value::Table(l) => {
+        UntaggedValue::Table(l) => {
             let mut out = vec![];
 
             for value in l {
@@ -78,14 +83,14 @@ pub fn value_to_yaml_value(v: &Tagged<Value>) -> Result<serde_yaml::Value, Shell
 
             serde_yaml::Value::Sequence(out)
         }
-        Value::Error(e) => return Err(e.clone()),
-        Value::Block(_) => serde_yaml::Value::Null,
-        Value::Primitive(Primitive::Binary(b)) => serde_yaml::Value::Sequence(
+        UntaggedValue::Error(e) => return Err(e.clone()),
+        UntaggedValue::Block(_) => serde_yaml::Value::Null,
+        UntaggedValue::Primitive(Primitive::Binary(b)) => serde_yaml::Value::Sequence(
             b.iter()
                 .map(|x| serde_yaml::Value::Number(serde_yaml::Number::from(*x)))
                 .collect(),
         ),
-        Value::Row(o) => {
+        UntaggedValue::Row(o) => {
             let mut m = serde_yaml::Mapping::new();
             for (k, v) in o.entries.iter() {
                 m.insert(
@@ -101,12 +106,14 @@ pub fn value_to_yaml_value(v: &Tagged<Value>) -> Result<serde_yaml::Value, Shell
 fn to_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
     let name_tag = args.name_tag();
+    let name_span = name_tag.span;
+
     let stream = async_stream! {
-        let input: Vec<Tagged<Value>> = args.input.values.collect().await;
+        let input: Vec<Value> = args.input.values.collect().await;
 
         let to_process_input = if input.len() > 1 {
             let tag = input[0].tag.clone();
-            vec![Tagged { item: Value::Table(input), tag } ]
+            vec![Value { value: UntaggedValue::Table(input), tag } ]
         } else if input.len() == 1 {
             input
         } else {
@@ -114,18 +121,20 @@ fn to_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream
         };
 
         for value in to_process_input {
+            let value_span = value.tag.span;
+
             match value_to_yaml_value(&value) {
                 Ok(yaml_value) => {
                     match serde_yaml::to_string(&yaml_value) {
                         Ok(x) => yield ReturnSuccess::value(
-                            Value::Primitive(Primitive::String(x)).tagged(&name_tag),
+                            UntaggedValue::Primitive(Primitive::String(x)).into_value(&name_tag),
                         ),
                         _ => yield Err(ShellError::labeled_error_with_secondary(
                             "Expected a table with YAML-compatible structure.tag() from pipeline",
                             "requires YAML-compatible input",
-                            &name_tag,
+                            name_span,
                             "originates from here".to_string(),
-                            value.tag(),
+                            value_span,
                         )),
                     }
                 }

src/commands/trim.rs

@@ -1,5 +1,5 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::Value;
+
 use crate::errors::ShellError;
 use crate::prelude::*;
 
@@ -34,7 +34,7 @@ fn trim(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream,
         .values
         .map(move |v| {
             let string = String::extract(&v)?;
-            ReturnSuccess::value(Value::string(string.trim()).tagged(v.tag()))
+            ReturnSuccess::value(UntaggedValue::string(string.trim()).into_value(v.tag()))
         })
         .to_output_stream())
 }

src/commands/version.rs

@@ -1,5 +1,5 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::{Dictionary, Value};
+use crate::data::Dictionary;
 use crate::errors::ShellError;
 use crate::parser::registry::Signature;
 use crate::prelude::*;
@@ -36,9 +36,9 @@ pub fn date(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
     let mut indexmap = IndexMap::new();
     indexmap.insert(
         "version".to_string(),
-        Value::string(clap::crate_version!()).tagged(&tag),
+        UntaggedValue::string(clap::crate_version!()).into_value(&tag),
     );
 
-    let value = Value::Row(Dictionary::from(indexmap)).tagged(&tag);
+    let value = UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag);
     Ok(OutputStream::one(value))
 }

src/commands/what.rs

@@ -1,5 +1,5 @@
 use crate::commands::WholeStreamCommand;
-use crate::data::Value;
+
 use crate::errors::ShellError;
 use crate::prelude::*;
 use futures::StreamExt;
@@ -41,8 +41,8 @@ pub fn what(
         pin_mut!(values);
 
         while let Some(row) = values.next().await {
-            let name = row.format_leaf().pretty_debug().plain_string(100000);
-            yield ReturnSuccess::value(Value::string(name).tagged(Tag::unknown_anchor(row.tag.span)));
+            let name = row.format_leaf().plain_string(100000);
+            yield ReturnSuccess::value(UntaggedValue::string(name).into_value(Tag::unknown_anchor(row.tag.span)));
         }
     };
 

src/commands/where_.rs

@@ -28,13 +28,13 @@ impl PerItemCommand for Where {
         call_info: &CallInfo,
         _registry: &registry::CommandRegistry,
         _raw_args: &RawCommandArgs,
-        input: Tagged<Value>,
+        input: Value,
     ) -> Result<OutputStream, ShellError> {
         let input_clone = input.clone();
         let condition = call_info.args.expect_nth(0)?;
         let stream = match condition {
-            Tagged {
-                item: Value::Block(block),
+            Value {
+                value: UntaggedValue::Block(block),
                 ..
             } => {
                 let result = block.invoke(&input_clone);
@@ -49,7 +49,7 @@ impl PerItemCommand for Where {
                     Err(e) => return Err(e),
                 }
             }
-            Tagged { tag, .. } => {
+            Value { tag, .. } => {
                 return Err(ShellError::labeled_error(
                     "Expected a condition",
                     "where needs a condition",

src/commands/which_.rs

@@ -42,17 +42,18 @@ pub fn which(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStre
     if let Some(v) = &args.call_info.args.positional {
         if v.len() > 0 {
             match &v[0] {
-                Tagged {
-                    item: Value::Primitive(Primitive::String(s)),
+                Value {
+                    value: UntaggedValue::Primitive(Primitive::String(s)),
                     tag,
                 } => match which::which(&s) {
                     Ok(ok) => {
-                        which_out
-                            .push_back(Value::Primitive(Primitive::Path(ok)).tagged(tag.clone()));
+                        which_out.push_back(
+                            UntaggedValue::Primitive(Primitive::Path(ok)).into_value(tag.clone()),
+                        );
                     }
                     _ => {}
                 },
-                Tagged { tag, .. } => {
+                Value { tag, .. } => {
                     return Err(ShellError::labeled_error(
                         "Expected a filename to find",
                         "needs a filename",

src/context.rs

@@ -1,19 +1,16 @@
-use crate::commands::{Command, UnevaluatedCallInfo};
+use crate::commands::{command::CommandArgs, Command, UnevaluatedCallInfo};
+use crate::env::host::Host;
+use crate::errors::ShellError;
 use crate::parser::{hir, hir::syntax_shape::ExpandContext};
-use crate::prelude::*;
+use crate::shell::shell_manager::ShellManager;
+use crate::stream::{InputStream, OutputStream};
 use indexmap::IndexMap;
-use serde::{Deserialize, Serialize};
+use nu_source::Tag;
+use nu_source::Text;
 use std::error::Error;
 use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Mutex};
 
-#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub enum AnchorLocation {
-    Url(String),
-    File(String),
-    Source(Text),
-}
-
 #[derive(Clone)]
 pub struct CommandRegistry {
     registry: Arc<Mutex<IndexMap<String, Arc<Command>>>>,

src/data.rs

@@ -4,7 +4,6 @@ pub(crate) mod config;
 pub(crate) mod dict;
 pub(crate) mod files;
 pub(crate) mod into;
-pub(crate) mod meta;
 pub(crate) mod types;
 
 pub(crate) use base::{Primitive, Value};

src/data/base.rs

@@ -3,19 +3,19 @@ mod property_get;
 pub(crate) mod shape;
 
 use crate::context::CommandRegistry;
-use crate::data::base::shape::{InlineShape, TypeShape};
+use crate::data::base::shape::{Column, InlineShape, TypeShape};
 use crate::data::TaggedDictBuilder;
 use crate::errors::ShellError;
 use crate::evaluate::{evaluate_baseline_expr, Scope};
 use crate::parser::hir::path::{ColumnPath, PathMember};
 use crate::parser::{hir, Operator};
 use crate::prelude::*;
-use crate::Text;
 use chrono::{DateTime, Utc};
 use chrono_humanize::Humanize;
 use derive_new::new;
 use indexmap::IndexMap;
 use log::trace;
+use nu_source::{AnchorLocation, PrettyDebug, SpannedItem, Tagged, TaggedItem, Text};
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 use std::time::SystemTime;
@@ -171,12 +171,12 @@ impl Primitive {
                     &members
                         .next()
                         .expect("BUG: column path with zero members")
-                        .to_string(),
+                        .display(),
                 );
 
                 for member in members {
                     f.push_str(".");
-                    f.push_str(&member.to_string())
+                    f.push_str(&member.display())
                 }
 
                 f
@@ -232,11 +232,11 @@ pub struct Block {
 }
 
 impl Block {
-    pub fn invoke(&self, value: &Tagged<Value>) -> Result<Tagged<Value>, ShellError> {
+    pub fn invoke(&self, value: &Value) -> Result<Value, ShellError> {
         let scope = Scope::new(value.clone());
 
         if self.expressions.len() == 0 {
-            return Ok(Value::nothing().tagged(&self.tag));
+            return Ok(UntaggedValue::nothing().into_value(&self.tag));
         }
 
         let mut last = None;
@@ -263,10 +263,10 @@ impl Block {
 }
 
 #[derive(Debug, Eq, PartialEq, Ord, PartialOrd, Clone, Serialize, Deserialize)]
-pub enum Value {
+pub enum UntaggedValue {
     Primitive(Primitive),
     Row(crate::data::Dictionary),
-    Table(Vec<Tagged<Value>>),
+    Table(Vec<Value>),
 
     // Errors are a type of value too
     Error(ShellError),
@@ -274,191 +274,104 @@ pub enum Value {
     Block(Block),
 }
 
+#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
+pub struct Value {
+    pub value: UntaggedValue,
+    pub tag: Tag,
+}
+
+impl std::ops::Deref for Value {
+    type Target = UntaggedValue;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+
+impl Into<UntaggedValue> for Value {
+    fn into(self) -> UntaggedValue {
+        self.value
+    }
+}
+
+impl<'a> Into<&'a UntaggedValue> for &'a Value {
+    fn into(self) -> &'a UntaggedValue {
+        &self.value
+    }
+}
+
+impl HasSpan for Value {
+    fn span(&self) -> Span {
+        self.tag.span
+    }
+}
+
 impl ShellTypeName for Value {
     fn type_name(&self) -> &'static str {
+        ShellTypeName::type_name(&self.value)
+    }
+}
+
+impl ShellTypeName for UntaggedValue {
+    fn type_name(&self) -> &'static str {
+        match &self {
+            UntaggedValue::Primitive(p) => p.type_name(),
+            UntaggedValue::Row(_) => "row",
+            UntaggedValue::Table(_) => "table",
+            UntaggedValue::Error(_) => "error",
+            UntaggedValue::Block(_) => "block",
+        }
+    }
+}
+
+impl Into<UntaggedValue> for Number {
+    fn into(self) -> UntaggedValue {
         match self {
-            Value::Primitive(p) => p.type_name(),
-            Value::Row(_) => "row",
-            Value::Table(_) => "table",
-            Value::Error(_) => "error",
-            Value::Block(_) => "block",
+            Number::Int(int) => UntaggedValue::int(int),
+            Number::Decimal(decimal) => UntaggedValue::decimal(decimal),
         }
     }
 }
 
-impl Into<Value> for Number {
-    fn into(self) -> Value {
+impl Into<UntaggedValue> for &Number {
+    fn into(self) -> UntaggedValue {
         match self {
-            Number::Int(int) => Value::int(int),
-            Number::Decimal(decimal) => Value::decimal(decimal),
-        }
-    }
-}
-
-impl Into<Value> for &Number {
-    fn into(self) -> Value {
-        match self {
-            Number::Int(int) => Value::int(int.clone()),
-            Number::Decimal(decimal) => Value::decimal(decimal.clone()),
-        }
-    }
-}
-
-impl Tagged<Value> {
-    pub fn tagged_type_name(&self) -> Tagged<String> {
-        let name = self.type_name().to_string();
-        name.tagged(self.tag())
-    }
-}
-
-impl Tagged<&Value> {
-    pub fn tagged_type_name(&self) -> Tagged<String> {
-        let name = self.type_name().to_string();
-        name.tagged(self.tag())
-    }
-}
-
-impl std::convert::TryFrom<&Tagged<Value>> for Block {
-    type Error = ShellError;
-
-    fn try_from(value: &Tagged<Value>) -> Result<Block, ShellError> {
-        match value.item() {
-            Value::Block(block) => Ok(block.clone()),
-            v => Err(ShellError::type_error(
-                "Block",
-                v.type_name().spanned(value.span()),
-            )),
-        }
-    }
-}
-
-impl std::convert::TryFrom<&Tagged<Value>> for i64 {
-    type Error = ShellError;
-
-    fn try_from(value: &Tagged<Value>) -> Result<i64, ShellError> {
-        match value.item() {
-            Value::Primitive(Primitive::Int(int)) => {
-                int.tagged(&value.tag).coerce_into("converting to i64")
-            }
-            v => Err(ShellError::type_error(
-                "Integer",
-                v.type_name().spanned(value.span()),
-            )),
-        }
-    }
-}
-
-impl std::convert::TryFrom<&Tagged<Value>> for String {
-    type Error = ShellError;
-
-    fn try_from(value: &Tagged<Value>) -> Result<String, ShellError> {
-        match value.item() {
-            Value::Primitive(Primitive::String(s)) => Ok(s.clone()),
-            v => Err(ShellError::type_error(
-                "String",
-                v.type_name().spanned(value.span()),
-            )),
-        }
-    }
-}
-
-impl std::convert::TryFrom<&Tagged<Value>> for Vec<u8> {
-    type Error = ShellError;
-
-    fn try_from(value: &Tagged<Value>) -> Result<Vec<u8>, ShellError> {
-        match value.item() {
-            Value::Primitive(Primitive::Binary(b)) => Ok(b.clone()),
-            v => Err(ShellError::type_error(
-                "Binary",
-                v.type_name().spanned(value.span()),
-            )),
-        }
-    }
-}
-
-impl<'a> std::convert::TryFrom<&'a Tagged<Value>> for &'a crate::data::Dictionary {
-    type Error = ShellError;
-
-    fn try_from(value: &'a Tagged<Value>) -> Result<&'a crate::data::Dictionary, ShellError> {
-        match value.item() {
-            Value::Row(d) => Ok(d),
-            v => Err(ShellError::type_error(
-                "Dictionary",
-                v.type_name().spanned(value.span()),
-            )),
-        }
-    }
-}
-
-#[derive(Serialize, Deserialize)]
-pub enum Switch {
-    Present,
-    Absent,
-}
-
-impl std::convert::TryFrom<Option<&Tagged<Value>>> for Switch {
-    type Error = ShellError;
-
-    fn try_from(value: Option<&Tagged<Value>>) -> Result<Switch, ShellError> {
-        match value {
-            None => Ok(Switch::Absent),
-            Some(value) => match value.item() {
-                Value::Primitive(Primitive::Boolean(true)) => Ok(Switch::Present),
-                v => Err(ShellError::type_error(
-                    "Boolean",
-                    v.type_name().spanned(value.span()),
-                )),
-            },
+            Number::Int(int) => UntaggedValue::int(int.clone()),
+            Number::Decimal(decimal) => UntaggedValue::decimal(decimal.clone()),
         }
     }
 }
 
 impl Value {
-    pub fn data_descriptors(&self) -> Vec<String> {
-        match self {
-            Value::Primitive(_) => vec![],
-            Value::Row(columns) => columns
-                .entries
-                .keys()
-                .into_iter()
-                .map(|x| x.to_string())
-                .collect(),
-            Value::Block(_) => vec![],
-            Value::Table(_) => vec![],
-            Value::Error(_) => vec![],
+    pub fn anchor(&self) -> Option<AnchorLocation> {
+        self.tag.anchor()
+    }
+
+    pub fn anchor_name(&self) -> Option<String> {
+        self.tag.anchor_name()
+    }
+
+    pub fn tag(&self) -> Tag {
+        self.tag.clone()
+    }
+
+    pub fn into_parts(self) -> (UntaggedValue, Tag) {
+        (self.value, self.tag)
+    }
+
+    pub(crate) fn as_path(&self) -> Result<PathBuf, ShellError> {
+        match &self.value {
+            UntaggedValue::Primitive(Primitive::Path(path)) => Ok(path.clone()),
+            UntaggedValue::Primitive(Primitive::String(path_str)) => {
+                Ok(PathBuf::from(&path_str).clone())
+            }
+            _ => Err(ShellError::type_error("Path", self.spanned_type_name())),
         }
     }
 
-    pub fn get_data(&self, desc: &String) -> MaybeOwned<'_, Value> {
-        match self {
-            p @ Value::Primitive(_) => MaybeOwned::Borrowed(p),
-            Value::Row(o) => o.get_data(desc),
-            Value::Block(_) => MaybeOwned::Owned(Value::nothing()),
-            Value::Table(_) => MaybeOwned::Owned(Value::nothing()),
-            Value::Error(_) => MaybeOwned::Owned(Value::nothing()),
-        }
-    }
-
-    #[allow(unused)]
-    pub(crate) fn format_type(&self, width: usize) -> String {
-        TypeShape::from_value(self).colored_string(width)
-    }
-
-    pub(crate) fn format_leaf(&self) -> DebugDocBuilder {
-        InlineShape::from_value(self).format().pretty_debug()
-    }
-
-    // pub(crate) fn format_for_column(&self, column: impl Into<Column>) -> DebugDocBuilder {
-    //     InlineShape::from_value(self)
-    //         .format_for_column(column)
-    //         .pretty_debug()
-    // }
-
-    pub(crate) fn style_leaf(&self) -> &'static str {
-        match self {
-            Value::Primitive(p) => p.style(),
-            _ => "",
-        }
+    pub fn tagged_type_name(&self) -> Tagged<String> {
+        let name = self.type_name().to_string();
+        name.tagged(self.tag.clone())
     }
 
     pub(crate) fn compare(
@@ -490,10 +403,174 @@ impl Value {
             }
         }
     }
+}
+
+impl PrettyDebug for &Value {
+    fn pretty(&self) -> DebugDocBuilder {
+        PrettyDebug::pretty(*self)
+    }
+}
+
+impl PrettyDebug for Value {
+    fn pretty(&self) -> DebugDocBuilder {
+        match &self.value {
+            UntaggedValue::Primitive(p) => p.pretty(),
+            UntaggedValue::Row(row) => row.pretty_builder().nest(1).group().into(),
+            UntaggedValue::Table(table) => {
+                b::delimit("[", b::intersperse(table, b::space()), "]").nest()
+            }
+            UntaggedValue::Error(_) => b::error("error"),
+            UntaggedValue::Block(_) => b::opaque("block"),
+        }
+    }
+}
+
+impl std::convert::TryFrom<&Value> for Block {
+    type Error = ShellError;
+
+    fn try_from(value: &Value) -> Result<Block, ShellError> {
+        match &value.value {
+            UntaggedValue::Block(block) => Ok(block.clone()),
+            _ => Err(ShellError::type_error(
+                "Block",
+                value.type_name().spanned(value.tag.span),
+            )),
+        }
+    }
+}
+
+impl std::convert::TryFrom<&Value> for i64 {
+    type Error = ShellError;
+
+    fn try_from(value: &Value) -> Result<i64, ShellError> {
+        match &value.value {
+            UntaggedValue::Primitive(Primitive::Int(int)) => {
+                int.tagged(&value.tag).coerce_into("converting to i64")
+            }
+            _ => Err(ShellError::type_error("Integer", value.spanned_type_name())),
+        }
+    }
+}
+
+impl std::convert::TryFrom<&Value> for String {
+    type Error = ShellError;
+
+    fn try_from(value: &Value) -> Result<String, ShellError> {
+        match &value.value {
+            UntaggedValue::Primitive(Primitive::String(s)) => Ok(s.clone()),
+            _ => Err(ShellError::type_error("String", value.spanned_type_name())),
+        }
+    }
+}
+
+impl std::convert::TryFrom<&Value> for Vec<u8> {
+    type Error = ShellError;
+
+    fn try_from(value: &Value) -> Result<Vec<u8>, ShellError> {
+        match &value.value {
+            UntaggedValue::Primitive(Primitive::Binary(b)) => Ok(b.clone()),
+            _ => Err(ShellError::type_error("Binary", value.spanned_type_name())),
+        }
+    }
+}
+
+impl<'a> std::convert::TryFrom<&'a Value> for &'a crate::data::Dictionary {
+    type Error = ShellError;
+
+    fn try_from(value: &'a Value) -> Result<&'a crate::data::Dictionary, ShellError> {
+        match &value.value {
+            UntaggedValue::Row(d) => Ok(d),
+            _ => Err(ShellError::type_error(
+                "Dictionary",
+                value.spanned_type_name(),
+            )),
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+pub enum Switch {
+    Present,
+    Absent,
+}
+
+impl std::convert::TryFrom<Option<&Value>> for Switch {
+    type Error = ShellError;
+
+    fn try_from(value: Option<&Value>) -> Result<Switch, ShellError> {
+        match value {
+            None => Ok(Switch::Absent),
+            Some(value) => match &value.value {
+                UntaggedValue::Primitive(Primitive::Boolean(true)) => Ok(Switch::Present),
+                _ => Err(ShellError::type_error("Boolean", value.spanned_type_name())),
+            },
+        }
+    }
+}
+
+impl UntaggedValue {
+    pub fn into_value(self, tag: impl Into<Tag>) -> Value {
+        Value {
+            value: self,
+            tag: tag.into(),
+        }
+    }
+
+    pub fn into_untagged_value(self) -> Value {
+        Value {
+            value: self,
+            tag: Tag::unknown(),
+        }
+    }
+
+    pub fn retag(self, tag: impl Into<Tag>) -> Value {
+        Value {
+            value: self,
+            tag: tag.into(),
+        }
+    }
+
+    pub fn data_descriptors(&self) -> Vec<String> {
+        match self {
+            UntaggedValue::Primitive(_) => vec![],
+            UntaggedValue::Row(columns) => columns
+                .entries
+                .keys()
+                .into_iter()
+                .map(|x| x.to_string())
+                .collect(),
+            UntaggedValue::Block(_) => vec![],
+            UntaggedValue::Table(_) => vec![],
+            UntaggedValue::Error(_) => vec![],
+        }
+    }
+
+    #[allow(unused)]
+    pub(crate) fn format_type(&self, width: usize) -> String {
+        TypeShape::from_value(self).colored_string(width)
+    }
+
+    pub(crate) fn format_leaf(&self) -> DebugDocBuilder {
+        InlineShape::from_value(self).format().pretty()
+    }
+
+    #[allow(unused)]
+    pub(crate) fn format_for_column(&self, column: impl Into<Column>) -> DebugDocBuilder {
+        InlineShape::from_value(self)
+            .format_for_column(column)
+            .pretty()
+    }
+
+    pub(crate) fn style_leaf(&self) -> &'static str {
+        match self {
+            UntaggedValue::Primitive(p) => p.style(),
+            _ => "",
+        }
+    }
 
     pub(crate) fn is_true(&self) -> bool {
         match self {
-            Value::Primitive(Primitive::Boolean(true)) => true,
+            UntaggedValue::Primitive(Primitive::Boolean(true)) => true,
             _ => false,
         }
     }
@@ -504,90 +581,97 @@ impl Value {
 
     pub(crate) fn is_none(&self) -> bool {
         match self {
-            Value::Primitive(Primitive::Nothing) => true,
+            UntaggedValue::Primitive(Primitive::Nothing) => true,
             _ => false,
         }
     }
 
     pub(crate) fn is_error(&self) -> bool {
         match self {
-            Value::Error(_err) => true,
+            UntaggedValue::Error(_err) => true,
             _ => false,
         }
     }
 
     pub(crate) fn expect_error(&self) -> ShellError {
         match self {
-            Value::Error(err) => err.clone(),
+            UntaggedValue::Error(err) => err.clone(),
             _ => panic!("Don't call expect_error without first calling is_error"),
         }
     }
 
+    pub fn expect_string(&self) -> &str {
+        match self {
+            UntaggedValue::Primitive(Primitive::String(string)) => &string[..],
+            _ => panic!("expect_string assumes that the value must be a string"),
+        }
+    }
+
     #[allow(unused)]
-    pub fn row(entries: IndexMap<String, Tagged<Value>>) -> Value {
-        Value::Row(entries.into())
+    pub fn row(entries: IndexMap<String, Value>) -> UntaggedValue {
+        UntaggedValue::Row(entries.into())
     }
 
-    pub fn table(list: &Vec<Tagged<Value>>) -> Value {
-        Value::Table(list.to_vec())
+    pub fn table(list: &Vec<Value>) -> UntaggedValue {
+        UntaggedValue::Table(list.to_vec())
     }
 
-    pub fn string(s: impl Into<String>) -> Value {
-        Value::Primitive(Primitive::String(s.into()))
+    pub fn string(s: impl Into<String>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::String(s.into()))
     }
 
-    pub fn column_path(s: Vec<impl Into<PathMember>>) -> Value {
-        Value::Primitive(Primitive::ColumnPath(ColumnPath::new(
+    pub fn column_path(s: Vec<impl Into<PathMember>>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::ColumnPath(ColumnPath::new(
             s.into_iter().map(|p| p.into()).collect(),
         )))
     }
 
-    pub fn int(i: impl Into<BigInt>) -> Value {
-        Value::Primitive(Primitive::Int(i.into()))
+    pub fn int(i: impl Into<BigInt>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Int(i.into()))
     }
 
-    pub fn pattern(s: impl Into<String>) -> Value {
-        Value::Primitive(Primitive::String(s.into()))
+    pub fn pattern(s: impl Into<String>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::String(s.into()))
     }
 
-    pub fn path(s: impl Into<PathBuf>) -> Value {
-        Value::Primitive(Primitive::Path(s.into()))
+    pub fn path(s: impl Into<PathBuf>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Path(s.into()))
     }
 
-    pub fn bytes(s: impl Into<u64>) -> Value {
-        Value::Primitive(Primitive::Bytes(s.into()))
+    pub fn bytes(s: impl Into<u64>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Bytes(s.into()))
     }
 
-    pub fn decimal(s: impl Into<BigDecimal>) -> Value {
-        Value::Primitive(Primitive::Decimal(s.into()))
+    pub fn decimal(s: impl Into<BigDecimal>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Decimal(s.into()))
     }
 
-    pub fn binary(binary: Vec<u8>) -> Value {
-        Value::Primitive(Primitive::Binary(binary))
+    pub fn binary(binary: Vec<u8>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Binary(binary))
     }
 
-    pub fn number(s: impl Into<Number>) -> Value {
+    pub fn number(s: impl Into<Number>) -> UntaggedValue {
         let num = s.into();
 
         match num {
-            Number::Int(int) => Value::int(int),
-            Number::Decimal(decimal) => Value::decimal(decimal),
+            Number::Int(int) => UntaggedValue::int(int),
+            Number::Decimal(decimal) => UntaggedValue::decimal(decimal),
         }
     }
 
-    pub fn boolean(s: impl Into<bool>) -> Value {
-        Value::Primitive(Primitive::Boolean(s.into()))
+    pub fn boolean(s: impl Into<bool>) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Boolean(s.into()))
     }
 
-    pub fn duration(secs: u64) -> Value {
-        Value::Primitive(Primitive::Duration(secs))
+    pub fn duration(secs: u64) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Duration(secs))
     }
 
-    pub fn system_date(s: SystemTime) -> Value {
-        Value::Primitive(Primitive::Date(s.into()))
+    pub fn system_date(s: SystemTime) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Date(s.into()))
     }
 
-    pub fn date_from_str(s: Tagged<&str>) -> Result<Value, ShellError> {
+    pub fn date_from_str(s: Tagged<&str>) -> Result<UntaggedValue, ShellError> {
         let date = DateTime::parse_from_rfc3339(s.item).map_err(|err| {
             ShellError::labeled_error(
                 &format!("Date parse error: {}", err),
@@ -598,43 +682,30 @@ impl Value {
 
         let date = date.with_timezone(&chrono::offset::Utc);
 
-        Ok(Value::Primitive(Primitive::Date(date)))
+        Ok(UntaggedValue::Primitive(Primitive::Date(date)))
     }
 
-    pub fn nothing() -> Value {
-        Value::Primitive(Primitive::Nothing)
+    pub fn nothing() -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::Nothing)
     }
 }
 
-impl Tagged<Value> {
-    pub(crate) fn as_path(&self) -> Result<PathBuf, ShellError> {
-        match self.item() {
-            Value::Primitive(Primitive::Path(path)) => Ok(path.clone()),
-            Value::Primitive(Primitive::String(path_str)) => Ok(PathBuf::from(&path_str).clone()),
-            other => Err(ShellError::type_error(
-                "Path",
-                other.type_name().spanned(self.span()),
-            )),
-        }
-    }
-}
-
-pub(crate) fn select_fields(obj: &Value, fields: &[String], tag: impl Into<Tag>) -> Tagged<Value> {
+pub(crate) fn select_fields(obj: &Value, fields: &[String], tag: impl Into<Tag>) -> Value {
     let mut out = TaggedDictBuilder::new(tag);
 
     let descs = obj.data_descriptors();
 
     for field in fields {
         match descs.iter().find(|d| *d == field) {
-            None => out.insert(field, Value::nothing()),
-            Some(desc) => out.insert(desc.clone(), obj.get_data(desc).borrow().clone()),
+            None => out.insert_untagged(field, UntaggedValue::nothing()),
+            Some(desc) => out.insert_value(desc.clone(), obj.get_data(desc).borrow().clone()),
         }
     }
 
-    out.into_tagged_value()
+    out.into_value()
 }
 
-pub(crate) fn reject_fields(obj: &Value, fields: &[String], tag: impl Into<Tag>) -> Tagged<Value> {
+pub(crate) fn reject_fields(obj: &Value, fields: &[String], tag: impl Into<Tag>) -> Value {
     let mut out = TaggedDictBuilder::new(tag);
 
     let descs = obj.data_descriptors();
@@ -643,11 +714,11 @@ pub(crate) fn reject_fields(obj: &Value, fields: &[String], tag: impl Into<Tag>)
         if fields.iter().any(|field| *field == desc) {
             continue;
         } else {
-            out.insert(desc.clone(), obj.get_data(&desc).borrow().clone())
+            out.insert_value(desc.clone(), obj.get_data(&desc).borrow().clone())
         }
     }
 
-    out.into_tagged_value()
+    out.into_value()
 }
 
 enum CompareValues {
@@ -680,8 +751,10 @@ fn coerce_compare(
     left: &Value,
     right: &Value,
 ) -> Result<CompareValues, (&'static str, &'static str)> {
-    match (left, right) {
-        (Value::Primitive(left), Value::Primitive(right)) => coerce_compare_primitive(left, right),
+    match (&left.value, &right.value) {
+        (UntaggedValue::Primitive(left), UntaggedValue::Primitive(right)) => {
+            coerce_compare_primitive(left, right)
+        }
 
         _ => Err((left.type_name(), right.type_name())),
     }
@@ -719,28 +792,29 @@ fn coerce_compare_primitive(
 #[cfg(test)]
 mod tests {
 
-    use crate::data::meta::*;
+    use super::UntaggedValue;
     use crate::parser::hir::path::PathMember;
     use crate::ColumnPath as ColumnPathValue;
     use crate::ShellError;
     use crate::Value;
     use indexmap::IndexMap;
+    use nu_source::*;
     use num_bigint::BigInt;
 
-    fn string(input: impl Into<String>) -> Tagged<Value> {
-        Value::string(input.into()).tagged_unknown()
+    fn string(input: impl Into<String>) -> Value {
+        UntaggedValue::string(input.into()).into_untagged_value()
     }
 
-    fn int(input: impl Into<BigInt>) -> Tagged<Value> {
-        Value::int(input.into()).tagged_unknown()
+    fn int(input: impl Into<BigInt>) -> Value {
+        UntaggedValue::int(input.into()).into_untagged_value()
     }
 
-    fn row(entries: IndexMap<String, Tagged<Value>>) -> Tagged<Value> {
-        Value::row(entries).tagged_unknown()
+    fn row(entries: IndexMap<String, Value>) -> Value {
+        UntaggedValue::row(entries).into_untagged_value()
     }
 
-    fn table(list: &Vec<Tagged<Value>>) -> Tagged<Value> {
-        Value::table(list).tagged_unknown()
+    fn table(list: &Vec<Value>) -> Value {
+        UntaggedValue::table(list).into_untagged_value()
     }
 
     fn error_callback(
@@ -749,7 +823,7 @@ mod tests {
         move |(_obj_source, _column_path_tried, _err)| ShellError::unimplemented(reason)
     }
 
-    fn column_path(paths: &Vec<Tagged<Value>>) -> Tagged<ColumnPathValue> {
+    fn column_path(paths: &Vec<Value>) -> Tagged<ColumnPathValue> {
         table(&paths.iter().cloned().collect())
             .as_column_path()
             .unwrap()
@@ -757,9 +831,10 @@ mod tests {
 
     #[test]
     fn gets_matching_field_from_a_row() {
-        let row = Value::row(indexmap! {
+        let row = UntaggedValue::row(indexmap! {
             "amigos".into() => table(&vec![string("andres"),string("jonathan"),string("yehuda")])
-        });
+        })
+        .into_untagged_value();
 
         assert_eq!(
             row.get_data_by_key("amigos".spanned_unknown()).unwrap(),
@@ -777,7 +852,7 @@ mod tests {
 
         let (version, tag) = string("0.4.0").into_parts();
 
-        let value = Value::row(indexmap! {
+        let value = UntaggedValue::row(indexmap! {
             "package".into() =>
                 row(indexmap! {
                     "name".into()    =>     string("nu"),
@@ -787,7 +862,7 @@ mod tests {
 
         assert_eq!(
             *value
-                .tagged(tag)
+                .into_value(tag)
                 .get_data_by_column_path(&field_path, Box::new(error_callback("package.version")))
                 .unwrap(),
             version
@@ -800,7 +875,7 @@ mod tests {
 
         let (_, tag) = string("Andrés N. Robalino").into_parts();
 
-        let value = Value::row(indexmap! {
+        let value = UntaggedValue::row(indexmap! {
             "package".into() => row(indexmap! {
                 "name".into() => string("nu"),
                 "version".into() => string("0.4.0"),
@@ -814,7 +889,7 @@ mod tests {
 
         assert_eq!(
             value
-                .tagged(tag)
+                .into_value(tag)
                 .get_data_by_column_path(
                     &field_path,
                     Box::new(error_callback("package.authors.name"))
@@ -834,7 +909,7 @@ mod tests {
 
         let (_, tag) = string("Andrés N. Robalino").into_parts();
 
-        let value = Value::row(indexmap! {
+        let value = UntaggedValue::row(indexmap! {
             "package".into() => row(indexmap! {
                 "name".into() => string("nu"),
                 "version".into() => string("0.4.0"),
@@ -848,10 +923,10 @@ mod tests {
 
         assert_eq!(
             *value
-                .tagged(tag)
+                .into_value(tag)
                 .get_data_by_column_path(&field_path, Box::new(error_callback("package.authors.0")))
                 .unwrap(),
-            Value::row(indexmap! {
+            UntaggedValue::row(indexmap! {
                 "name".into() => string("Andrés N. Robalino")
             })
         );
@@ -863,7 +938,7 @@ mod tests {
 
         let (_, tag) = string("Andrés N. Robalino").into_parts();
 
-        let value = Value::row(indexmap! {
+        let value = UntaggedValue::row(indexmap! {
             "package".into() => row(indexmap! {
                 "name".into() => string("nu"),
                 "version".into() => string("0.4.0"),
@@ -877,13 +952,13 @@ mod tests {
 
         assert_eq!(
             *value
-                .tagged(tag)
+                .into_value(tag)
                 .get_data_by_column_path(
                     &field_path,
                     Box::new(error_callback("package.authors.\"0\""))
                 )
                 .unwrap(),
-            Value::row(indexmap! {
+            UntaggedValue::row(indexmap! {
                 "name".into() => string("Andrés N. Robalino")
             })
         );
@@ -893,7 +968,7 @@ mod tests {
     fn replaces_matching_field_from_a_row() {
         let field_path = column_path(&vec![string("amigos")]);
 
-        let sample = Value::row(indexmap! {
+        let sample = UntaggedValue::row(indexmap! {
             "amigos".into() => table(&vec![
                 string("andres"),
                 string("jonathan"),
@@ -901,10 +976,10 @@ mod tests {
             ]),
         });
 
-        let (replacement, tag) = string("jonas").into_parts();
+        let replacement = string("jonas");
 
         let actual = sample
-            .tagged(tag)
+            .into_untagged_value()
             .replace_data_at_column_path(&field_path, replacement)
             .unwrap();
 
@@ -919,7 +994,7 @@ mod tests {
             string("los.3.caballeros"),
         ]);
 
-        let sample = Value::row(indexmap! {
+        let sample = UntaggedValue::row(indexmap! {
             "package".into() => row(indexmap! {
                 "authors".into() => row(indexmap! {
                     "los.3.mosqueteros".into() => table(&vec![string("andres::yehuda::jonathan")]),
@@ -929,22 +1004,23 @@ mod tests {
             })
         });
 
-        let (replacement, tag) = table(&vec![string("yehuda::jonathan::andres")]).into_parts();
+        let replacement = table(&vec![string("yehuda::jonathan::andres")]);
+        let tag = replacement.tag.clone();
 
         let actual = sample
-            .tagged(tag.clone())
+            .into_value(tag.clone())
             .replace_data_at_column_path(&field_path, replacement.clone())
             .unwrap();
 
         assert_eq!(
             actual,
-            Value::row(indexmap! {
+            UntaggedValue::row(indexmap! {
             "package".into() => row(indexmap! {
                 "authors".into() => row(indexmap! {
                     "los.3.mosqueteros".into() => table(&vec![string("andres::yehuda::jonathan")]),
                     "los.3.amigos".into()      => table(&vec![string("andres::yehuda::jonathan")]),
-                    "los.3.caballeros".into()  => replacement.tagged(&tag)})})})
-            .tagged(tag)
+                    "los.3.caballeros".into()  => replacement.clone()})})})
+            .into_value(tag)
         );
     }
     #[test]
@@ -955,7 +1031,7 @@ mod tests {
             string("nu.version.arepa"),
         ]);
 
-        let sample = Value::row(indexmap! {
+        let sample = UntaggedValue::row(indexmap! {
             "shell_policy".into() => row(indexmap! {
                 "releases".into() => table(&vec![
                     row(indexmap! {
@@ -977,24 +1053,24 @@ mod tests {
             })
         });
 
-        let (replacement, tag) = row(indexmap! {
+        let replacement = row(indexmap! {
             "code".into() => string("0.5.0"),
             "tag_line".into() => string("CABALLEROS")
-        })
-        .into_parts();
+        });
+        let tag = replacement.tag.clone();
 
         let actual = sample
-            .tagged(tag.clone())
+            .into_value(tag.clone())
             .replace_data_at_column_path(&field_path, replacement.clone())
             .unwrap();
 
         assert_eq!(
             actual,
-            Value::row(indexmap! {
+            UntaggedValue::row(indexmap! {
                 "shell_policy".into() => row(indexmap! {
                     "releases".into() => table(&vec![
                         row(indexmap! {
-                            "nu.version.arepa".into() => replacement.tagged(&tag)
+                            "nu.version.arepa".into() => replacement
                         }),
                         row(indexmap! {
                             "nu.version.taco".into() => row(indexmap! {
@@ -1008,7 +1084,7 @@ mod tests {
                         })
                     ])
                 })
-            }).tagged(&tag)
+            }).into_value(&tag)
         );
     }
 }

src/data/base/debug.rs

@@ -1,54 +1,6 @@
 use crate::data::base::Primitive;
-use crate::prelude::*;
-use crate::traits::DebugDocBuilder as b;
-use pretty::{BoxAllocator, DocAllocator};
-use std::fmt;
-
-impl FormatDebug for Tagged<Value> {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        match &self.item {
-            Value::Primitive(p) => p.fmt_debug(f, source),
-            Value::Row(row) => f.say_dict(
-                "row",
-                row.entries()
-                    .iter()
-                    .map(|(key, value)| (&key[..], format!("{}", value.debug(source))))
-                    .collect(),
-            ),
-            Value::Table(table) => f.say_list(
-                "table",
-                table,
-                |f| write!(f, "["),
-                |f, item| write!(f, "{}", item.debug(source)),
-                |f| write!(f, " "),
-                |f| write!(f, "]"),
-            ),
-            Value::Error(_) => f.say_simple("error"),
-            Value::Block(_) => f.say_simple("block"),
-        }
-    }
-}
-
-impl FormatDebug for Primitive {
-    fn fmt_debug(&self, f: &mut DebugFormatter, _source: &str) -> fmt::Result {
-        match self {
-            Primitive::Nothing => write!(f, "Nothing"),
-            Primitive::BeginningOfStream => write!(f, "BeginningOfStream"),
-            Primitive::EndOfStream => write!(f, "EndOfStream"),
-            Primitive::Int(int) => write!(f, "{}", int),
-            Primitive::Duration(duration) => write!(f, "{} seconds", *duration),
-            Primitive::Path(path) => write!(f, "{}", path.display()),
-            Primitive::Decimal(decimal) => write!(f, "{}", decimal),
-            Primitive::Bytes(bytes) => write!(f, "{}", bytes),
-            Primitive::Pattern(string) => write!(f, "{:?}", string),
-            Primitive::String(string) => write!(f, "{:?}", string),
-            Primitive::ColumnPath(path) => write!(f, "{:?}", path),
-            Primitive::Boolean(boolean) => write!(f, "{}", boolean),
-            Primitive::Date(date) => write!(f, "{}", date),
-            Primitive::Binary(binary) => write!(f, "{:?}", binary),
-        }
-    }
-}
+use crate::traits::PrettyType;
+use nu_source::{b, DebugDocBuilder, PrettyDebug};
 
 impl PrettyType for Primitive {
     fn pretty_type(&self) -> DebugDocBuilder {
@@ -72,14 +24,14 @@ impl PrettyType for Primitive {
 }
 
 impl PrettyDebug for Primitive {
-    fn pretty_debug(&self) -> DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
         match self {
             Primitive::Nothing => b::primitive("nothing"),
             Primitive::Int(int) => prim(format_args!("{}", int)),
             Primitive::Decimal(decimal) => prim(format_args!("{}", decimal)),
             Primitive::Bytes(bytes) => primitive_doc(bytes, "bytesize"),
             Primitive::String(string) => prim(string),
-            Primitive::ColumnPath(path) => path.pretty_debug(),
+            Primitive::ColumnPath(path) => path.pretty(),
             Primitive::Pattern(pattern) => primitive_doc(pattern, "pattern"),
             Primitive::Boolean(boolean) => match boolean {
                 true => b::primitive("$yes"),
@@ -95,27 +47,6 @@ impl PrettyDebug for Primitive {
     }
 }
 
-impl PrettyDebug for Value {
-    fn pretty_debug(&self) -> DebugDocBuilder {
-        match self {
-            Value::Primitive(p) => p.pretty_debug(),
-            Value::Row(row) => row.pretty_builder().nest(1).group().into(),
-            Value::Table(table) => BoxAllocator
-                .text("[")
-                .append(
-                    BoxAllocator
-                        .intersperse(table.iter().map(|v| v.item.to_doc()), BoxAllocator.space())
-                        .nest(1)
-                        .group(),
-                )
-                .append(BoxAllocator.text("]"))
-                .into(),
-            Value::Error(_) => b::error("error"),
-            Value::Block(_) => b::opaque("block"),
-        }
-    }
-}
-
 fn prim(name: impl std::fmt::Debug) -> DebugDocBuilder {
     b::primitive(format!("{:?}", name))
 }

src/data/base/property_get.rs

@@ -1,19 +1,17 @@
 use crate::errors::ExpectedRange;
-use crate::parser::hir::path::{PathMember, RawPathMember};
+use crate::parser::hir::path::{PathMember, UnspannedPathMember};
 use crate::prelude::*;
 use crate::ColumnPath;
 use crate::SpannedTypeName;
+use nu_source::{Spanned, SpannedItem, Tagged};
 
-impl Tagged<Value> {
-    pub(crate) fn get_data_by_member(
-        &self,
-        name: &PathMember,
-    ) -> Result<Tagged<Value>, ShellError> {
-        match &self.item {
+impl Value {
+    pub(crate) fn get_data_by_member(&self, name: &PathMember) -> Result<Value, ShellError> {
+        match &self.value {
             // If the value is a row, the member is a column name
-            Value::Row(o) => match &name.item {
+            UntaggedValue::Row(o) => match &name.unspanned {
                 // If the member is a string, get the data
-                RawPathMember::String(string) => o
+                UnspannedPathMember::String(string) => o
                     .get_data_by_key(string[..].spanned(name.span))
                     .ok_or_else(|| {
                         ShellError::missing_property(
@@ -23,62 +21,65 @@ impl Tagged<Value> {
                     }),
 
                 // If the member is a number, it's an error
-                RawPathMember::Int(_) => Err(ShellError::invalid_integer_index(
+                UnspannedPathMember::Int(_) => Err(ShellError::invalid_integer_index(
                     "row".spanned(self.tag.span),
                     name.span,
                 )),
             },
 
             // If the value is a table
-            Value::Table(l) => match &name.item {
-                // If the member is a string, map over the member
-                RawPathMember::String(string) => {
-                    let mut out = vec![];
+            UntaggedValue::Table(l) => {
+                match &name.unspanned {
+                    // If the member is a string, map over the member
+                    UnspannedPathMember::String(string) => {
+                        let mut out = vec![];
 
-                    for item in l {
-                        match item {
-                            Tagged {
-                                item: Value::Row(o),
-                                ..
-                            } => match o.get_data_by_key(string[..].spanned(name.span)) {
-                                Some(v) => out.push(v),
-                                None => {}
-                            },
-                            _ => {}
+                        for item in l {
+                            match item {
+                                Value {
+                                    value: UntaggedValue::Row(o),
+                                    ..
+                                } => match o.get_data_by_key(string[..].spanned(name.span)) {
+                                    Some(v) => out.push(v),
+                                    None => {}
+                                },
+                                _ => {}
+                            }
+                        }
+
+                        if out.len() == 0 {
+                            Err(ShellError::missing_property(
+                                "table".spanned(self.tag.span),
+                                string.spanned(name.span),
+                            ))
+                        } else {
+                            Ok(UntaggedValue::Table(out)
+                                .into_value(Tag::new(self.anchor(), name.span)))
                         }
                     }
+                    UnspannedPathMember::Int(int) => {
+                        let index = int.to_usize().ok_or_else(|| {
+                            ShellError::range_error(
+                                ExpectedRange::Usize,
+                                &"massive integer".spanned(name.span),
+                                "indexing",
+                            )
+                        })?;
 
-                    if out.len() == 0 {
-                        Err(ShellError::missing_property(
-                            "table".spanned(self.tag.span),
-                            string.spanned(name.span),
-                        ))
-                    } else {
-                        Ok(Value::Table(out).tagged(Tag::new(self.anchor(), name.span)))
+                        match self.get_data_by_index(index.spanned(self.tag.span)) {
+                            Some(v) => Ok(v.clone()),
+                            None => Err(ShellError::range_error(
+                                0..(l.len()),
+                                &int.spanned(name.span),
+                                "indexing",
+                            )),
+                        }
                     }
                 }
-                RawPathMember::Int(int) => {
-                    let index = int.to_usize().ok_or_else(|| {
-                        ShellError::range_error(
-                            ExpectedRange::Usize,
-                            &"massive integer".tagged(name.span),
-                            "indexing",
-                        )
-                    })?;
-
-                    match self.get_data_by_index(index.spanned(self.tag.span)) {
-                        Some(v) => Ok(v.clone()),
-                        None => Err(ShellError::range_error(
-                            0..(l.len()),
-                            &int.tagged(name.span),
-                            "indexing",
-                        )),
-                    }
-                }
-            },
+            }
             other => Err(ShellError::type_error(
                 "row or table",
-                other.spanned(self.tag.span).spanned_type_name(),
+                other.type_name().spanned(self.tag.span),
             )),
         }
     }
@@ -87,7 +88,7 @@ impl Tagged<Value> {
         &self,
         path: &ColumnPath,
         callback: Box<dyn FnOnce((&Value, &PathMember, ShellError)) -> ShellError>,
-    ) -> Result<Tagged<Value>, ShellError> {
+    ) -> Result<Value, ShellError> {
         let mut current = self.clone();
 
         for p in path.iter() {
@@ -102,19 +103,20 @@ impl Tagged<Value> {
         Ok(current)
     }
 
-    pub fn insert_data_at_path(&self, path: &str, new_value: Value) -> Option<Tagged<Value>> {
+    pub fn insert_data_at_path(&self, path: &str, new_value: Value) -> Option<Value> {
         let mut new_obj = self.clone();
 
         let split_path: Vec<_> = path.split(".").collect();
 
-        if let Value::Row(ref mut o) = new_obj.item {
+        if let UntaggedValue::Row(ref mut o) = new_obj.value {
             let mut current = o;
 
             if split_path.len() == 1 {
                 // Special case for inserting at the top level
-                current
-                    .entries
-                    .insert(path.to_string(), new_value.tagged(&self.tag));
+                current.entries.insert(
+                    path.to_string(),
+                    new_value.value.clone().into_value(&self.tag),
+                );
                 return Some(new_obj);
             }
 
@@ -122,11 +124,11 @@ impl Tagged<Value> {
                 match current.entries.get_mut(split_path[idx]) {
                     Some(next) => {
                         if idx == (split_path.len() - 2) {
-                            match &mut next.item {
-                                Value::Row(o) => {
+                            match &mut next.value {
+                                UntaggedValue::Row(o) => {
                                     o.entries.insert(
                                         split_path[idx + 1].to_string(),
-                                        new_value.tagged(&self.tag),
+                                        new_value.value.clone().into_value(&self.tag),
                                     );
                                 }
                                 _ => {}
@@ -134,8 +136,8 @@ impl Tagged<Value> {
 
                             return Some(new_obj.clone());
                         } else {
-                            match next.item {
-                                Value::Row(ref mut o) => {
+                            match next.value {
+                                UntaggedValue::Row(ref mut o) => {
                                     current = o;
                                 }
                                 _ => return None,
@@ -153,28 +155,28 @@ impl Tagged<Value> {
     pub fn insert_data_at_member(
         &mut self,
         member: &PathMember,
-        new_value: Tagged<Value>,
+        new_value: Value,
     ) -> Result<(), ShellError> {
-        match &mut self.item {
-            Value::Row(dict) => match &member.item {
-                RawPathMember::String(key) => Ok({
+        match &mut self.value {
+            UntaggedValue::Row(dict) => match &member.unspanned {
+                UnspannedPathMember::String(key) => Ok({
                     dict.insert_data_at_key(key, new_value);
                 }),
-                RawPathMember::Int(_) => Err(ShellError::type_error(
+                UnspannedPathMember::Int(_) => Err(ShellError::type_error(
                     "column name",
                     "integer".spanned(member.span),
                 )),
             },
-            Value::Table(array) => match &member.item {
-                RawPathMember::String(_) => Err(ShellError::type_error(
+            UntaggedValue::Table(array) => match &member.unspanned {
+                UnspannedPathMember::String(_) => Err(ShellError::type_error(
                     "list index",
                     "string".spanned(member.span),
                 )),
-                RawPathMember::Int(int) => Ok({
+                UnspannedPathMember::Int(int) => Ok({
                     let int = int.to_usize().ok_or_else(|| {
                         ShellError::range_error(
                             ExpectedRange::Usize,
-                            &"bigger number".tagged(member.span),
+                            &"bigger number".spanned(member.span),
                             "inserting into a list",
                         )
                     })?;
@@ -182,12 +184,12 @@ impl Tagged<Value> {
                     insert_data_at_index(array, int.tagged(member.span), new_value.clone())?;
                 }),
             },
-            other => match &member.item {
-                RawPathMember::String(_) => Err(ShellError::type_error(
+            other => match &member.unspanned {
+                UnspannedPathMember::String(_) => Err(ShellError::type_error(
                     "row",
                     other.type_name().spanned(self.span()),
                 )),
-                RawPathMember::Int(_) => Err(ShellError::type_error(
+                UnspannedPathMember::Int(_) => Err(ShellError::type_error(
                     "table",
                     other.type_name().spanned(self.span()),
                 )),
@@ -198,25 +200,22 @@ impl Tagged<Value> {
     pub fn insert_data_at_column_path(
         &self,
         split_path: &ColumnPath,
-        new_value: Tagged<Value>,
-    ) -> Result<Tagged<Value>, ShellError> {
+        new_value: Value,
+    ) -> Result<Value, ShellError> {
         let (last, front) = split_path.split_last();
         let mut original = self.clone();
 
-        let mut current: &mut Tagged<Value> = &mut original;
+        let mut current: &mut Value = &mut original;
 
         for member in front {
             let type_name = current.spanned_type_name();
 
-            current = current
-                .item
-                .get_mut_data_by_member(&member)
-                .ok_or_else(|| {
-                    ShellError::missing_property(
-                        member.plain_string(std::usize::MAX).spanned(member.span),
-                        type_name,
-                    )
-                })?
+            current = current.get_mut_data_by_member(&member).ok_or_else(|| {
+                ShellError::missing_property(
+                    member.plain_string(std::usize::MAX).spanned(member.span),
+                    type_name,
+                )
+            })?
         }
 
         current.insert_data_at_member(&last, new_value)?;
@@ -228,16 +227,16 @@ impl Tagged<Value> {
         &self,
         split_path: &ColumnPath,
         replaced_value: Value,
-    ) -> Option<Tagged<Value>> {
-        let mut new_obj: Tagged<Value> = self.clone();
+    ) -> Option<Value> {
+        let mut new_obj: Value = self.clone();
         let mut current = &mut new_obj;
         let split_path = split_path.members();
 
         for idx in 0..split_path.len() {
-            match current.item.get_mut_data_by_member(&split_path[idx]) {
+            match current.get_mut_data_by_member(&split_path[idx]) {
                 Some(next) => {
                     if idx == (split_path.len() - 1) {
-                        *next = replaced_value.tagged(&self.tag);
+                        *next = replaced_value.value.into_value(&self.tag);
                         return Some(new_obj);
                     } else {
                         current = next;
@@ -253,8 +252,8 @@ impl Tagged<Value> {
     }
 
     pub fn as_column_path(&self) -> Result<Tagged<ColumnPath>, ShellError> {
-        match &self.item {
-            Value::Table(table) => {
+        match &self.value {
+            UntaggedValue::Table(table) => {
                 let mut out: Vec<PathMember> = vec![];
 
                 for item in table {
@@ -264,7 +263,7 @@ impl Tagged<Value> {
                 Ok(ColumnPath::new(out).tagged(&self.tag))
             }
 
-            Value::Primitive(Primitive::ColumnPath(path)) => {
+            UntaggedValue::Primitive(Primitive::ColumnPath(path)) => {
                 Ok(path.clone().tagged(self.tag.clone()))
             }
 
@@ -276,8 +275,8 @@ impl Tagged<Value> {
     }
 
     pub fn as_path_member(&self) -> Result<PathMember, ShellError> {
-        match &self.item {
-            Value::Primitive(primitive) => match primitive {
+        match &self.value {
+            UntaggedValue::Primitive(primitive) => match primitive {
                 Primitive::Int(int) => Ok(PathMember::int(int.clone(), self.tag.span)),
                 Primitive::String(string) => Ok(PathMember::string(string, self.tag.span)),
                 other => Err(ShellError::type_error(
@@ -293,13 +292,13 @@ impl Tagged<Value> {
     }
 
     pub fn as_string(&self) -> Result<String, ShellError> {
-        match &self.item {
-            Value::Primitive(Primitive::String(s)) => Ok(s.clone()),
-            Value::Primitive(Primitive::Boolean(x)) => Ok(format!("{}", x)),
-            Value::Primitive(Primitive::Decimal(x)) => Ok(format!("{}", x)),
-            Value::Primitive(Primitive::Int(x)) => Ok(format!("{}", x)),
-            Value::Primitive(Primitive::Bytes(x)) => Ok(format!("{}", x)),
-            Value::Primitive(Primitive::Path(x)) => Ok(format!("{}", x.display())),
+        match &self.value {
+            UntaggedValue::Primitive(Primitive::String(s)) => Ok(s.clone()),
+            UntaggedValue::Primitive(Primitive::Boolean(x)) => Ok(format!("{}", x)),
+            UntaggedValue::Primitive(Primitive::Decimal(x)) => Ok(format!("{}", x)),
+            UntaggedValue::Primitive(Primitive::Int(x)) => Ok(format!("{}", x)),
+            UntaggedValue::Primitive(Primitive::Bytes(x)) => Ok(format!("{}", x)),
+            UntaggedValue::Primitive(Primitive::Path(x)) => Ok(format!("{}", x.display())),
             // TODO: this should definitely be more general with better errors
             other => Err(ShellError::labeled_error(
                 "Expected string",
@@ -311,14 +310,14 @@ impl Tagged<Value> {
 }
 
 fn insert_data_at_index(
-    list: &mut Vec<Tagged<Value>>,
+    list: &mut Vec<Value>,
     index: Tagged<usize>,
-    new_value: Tagged<Value>,
+    new_value: Value,
 ) -> Result<(), ShellError> {
     if list.len() >= index.item {
         Err(ShellError::range_error(
             0..(list.len()),
-            &format_args!("{}", index.item).tagged(index.tag.clone()),
+            &format_args!("{}", index.item).spanned(index.tag.span),
             "insert at index",
         ))
     } else {
@@ -328,41 +327,51 @@ fn insert_data_at_index(
 }
 
 impl Value {
-    pub(crate) fn get_data_by_index(&self, idx: Spanned<usize>) -> Option<Tagged<Value>> {
-        match self {
-            Value::Table(value_set) => {
+    pub fn get_data(&self, desc: &String) -> MaybeOwned<'_, Value> {
+        match &self.value {
+            UntaggedValue::Primitive(_) => MaybeOwned::Borrowed(self),
+            UntaggedValue::Row(o) => o.get_data(desc),
+            UntaggedValue::Block(_) | UntaggedValue::Table(_) | UntaggedValue::Error(_) => {
+                MaybeOwned::Owned(UntaggedValue::nothing().into_untagged_value())
+            }
+        }
+    }
+
+    pub(crate) fn get_data_by_index(&self, idx: Spanned<usize>) -> Option<Value> {
+        match &self.value {
+            UntaggedValue::Table(value_set) => {
                 let value = value_set.get(idx.item)?;
                 Some(
                     value
-                        .item
+                        .value
                         .clone()
-                        .tagged(Tag::new(value.anchor(), idx.span)),
+                        .into_value(Tag::new(value.anchor(), idx.span)),
                 )
             }
             _ => None,
         }
     }
 
-    pub(crate) fn get_data_by_key(&self, name: Spanned<&str>) -> Option<Tagged<Value>> {
-        match self {
-            Value::Row(o) => o.get_data_by_key(name),
-            Value::Table(l) => {
+    pub(crate) fn get_data_by_key(&self, name: Spanned<&str>) -> Option<Value> {
+        match &self.value {
+            UntaggedValue::Row(o) => o.get_data_by_key(name),
+            UntaggedValue::Table(l) => {
                 let mut out = vec![];
                 for item in l {
                     match item {
-                        Tagged {
-                            item: Value::Row(o),
+                        Value {
+                            value: UntaggedValue::Row(o),
                             ..
                         } => match o.get_data_by_key(name) {
                             Some(v) => out.push(v),
-                            None => out.push(Value::nothing().tagged_unknown()),
+                            None => out.push(UntaggedValue::nothing().into_untagged_value()),
                         },
-                        _ => out.push(Value::nothing().tagged_unknown()),
+                        _ => out.push(UntaggedValue::nothing().into_untagged_value()),
                     }
                 }
 
                 if out.len() > 0 {
-                    Some(Value::Table(out).tagged(name.span))
+                    Some(UntaggedValue::Table(out).into_value(name.span))
                 } else {
                     None
                 }
@@ -371,21 +380,18 @@ impl Value {
         }
     }
 
-    pub(crate) fn get_mut_data_by_member(
-        &mut self,
-        name: &PathMember,
-    ) -> Option<&mut Tagged<Value>> {
-        match self {
-            Value::Row(o) => match &name.item {
-                RawPathMember::String(string) => o.get_mut_data_by_key(&string),
-                RawPathMember::Int(_) => None,
+    pub(crate) fn get_mut_data_by_member(&mut self, name: &PathMember) -> Option<&mut Value> {
+        match &mut self.value {
+            UntaggedValue::Row(o) => match &name.unspanned {
+                UnspannedPathMember::String(string) => o.get_mut_data_by_key(&string),
+                UnspannedPathMember::Int(_) => None,
             },
-            Value::Table(l) => match &name.item {
-                RawPathMember::String(string) => {
+            UntaggedValue::Table(l) => match &name.unspanned {
+                UnspannedPathMember::String(string) => {
                     for item in l {
                         match item {
-                            Tagged {
-                                item: Value::Row(o),
+                            Value {
+                                value: UntaggedValue::Row(o),
                                 ..
                             } => match o.get_mut_data_by_key(&string) {
                                 Some(v) => return Some(v),
@@ -396,7 +402,7 @@ impl Value {
                     }
                     None
                 }
-                RawPathMember::Int(int) => {
+                UnspannedPathMember::Int(int) => {
                     let index = int.to_usize()?;
                     l.get_mut(index)
                 }

src/data/base/shape.rs

@@ -1,11 +1,12 @@
 use crate::data::base::{Block, ColumnPath};
 use crate::data::dict::Dictionary;
 use crate::prelude::*;
-use crate::traits::{DebugDocBuilder as b, PrettyDebug};
 use chrono::{DateTime, Utc};
 use chrono_humanize::Humanize;
 use derive_new::new;
 use indexmap::IndexMap;
+use nu_source::DebugDoc;
+use nu_source::{b, PrettyDebug};
 use std::collections::BTreeMap;
 use std::fmt::Debug;
 use std::hash::Hash;
@@ -76,7 +77,7 @@ impl TypeShape {
 
         for (key, value) in dictionary.entries.iter() {
             let column = Column::String(key.clone());
-            map.insert(column, TypeShape::from_value(&value.item));
+            map.insert(column, TypeShape::from_value(value));
         }
 
         TypeShape::Row(map)
@@ -92,19 +93,19 @@ impl TypeShape {
         TypeShape::Table(vec)
     }
 
-    pub fn from_value(value: &Value) -> TypeShape {
-        match value {
-            Value::Primitive(p) => TypeShape::from_primitive(p),
-            Value::Row(row) => TypeShape::from_dictionary(row),
-            Value::Table(table) => TypeShape::from_table(table.iter().map(|i| &i.item)),
-            Value::Error(_) => TypeShape::Error,
-            Value::Block(_) => TypeShape::Block,
+    pub fn from_value<'a>(value: impl Into<&'a UntaggedValue>) -> TypeShape {
+        match value.into() {
+            UntaggedValue::Primitive(p) => TypeShape::from_primitive(p),
+            UntaggedValue::Row(row) => TypeShape::from_dictionary(row),
+            UntaggedValue::Table(table) => TypeShape::from_table(table.iter()),
+            UntaggedValue::Error(_) => TypeShape::Error,
+            UntaggedValue::Block(_) => TypeShape::Block,
         }
     }
 }
 
 impl PrettyDebug for TypeShape {
-    fn pretty_debug(&self) -> DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
         match self {
             TypeShape::Nothing => ty("nothing"),
             TypeShape::Int => ty("integer"),
@@ -128,7 +129,7 @@ impl PrettyDebug for TypeShape {
                         (b::key(match key {
                             Column::String(string) => string.clone(),
                             Column::Value => "<value>".to_string(),
-                        }) + b::delimit("(", ty.pretty_debug(), ")").as_kind())
+                        }) + b::delimit("(", ty.pretty(), ")").as_kind())
                         .nest()
                     }),
                     b::space(),
@@ -186,11 +187,11 @@ struct DebugEntry<'a> {
 }
 
 impl<'a> PrettyDebug for DebugEntry<'a> {
-    fn pretty_debug(&self) -> DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
         (b::key(match self.key {
             Column::String(string) => string.clone(),
             Column::Value => format!("<value>"),
-        }) + b::delimit("(", self.value.pretty_debug(), ")").as_kind())
+        }) + b::delimit("(", self.value.pretty(), ")").as_kind())
     }
 }
 
@@ -256,7 +257,7 @@ impl InlineShape {
 
         for (key, value) in dictionary.entries.iter() {
             let column = Column::String(key.clone());
-            map.insert(column, InlineShape::from_value(&value.item));
+            map.insert(column, InlineShape::from_value(value));
         }
 
         InlineShape::Row(map)
@@ -272,22 +273,23 @@ impl InlineShape {
         InlineShape::Table(vec)
     }
 
-    pub fn from_value(value: &Value) -> InlineShape {
-        match value {
-            Value::Primitive(p) => InlineShape::from_primitive(p),
-            Value::Row(row) => InlineShape::from_dictionary(row),
-            Value::Table(table) => InlineShape::from_table(table.iter().map(|i| &i.item)),
-            Value::Error(_) => InlineShape::Error,
-            Value::Block(_) => InlineShape::Block,
+    pub fn from_value<'a>(value: impl Into<&'a UntaggedValue>) -> InlineShape {
+        match value.into() {
+            UntaggedValue::Primitive(p) => InlineShape::from_primitive(p),
+            UntaggedValue::Row(row) => InlineShape::from_dictionary(row),
+            UntaggedValue::Table(table) => InlineShape::from_table(table.iter()),
+            UntaggedValue::Error(_) => InlineShape::Error,
+            UntaggedValue::Block(_) => InlineShape::Block,
         }
     }
 
-    // pub fn format_for_column(self, column: impl Into<Column>) -> FormatInlineShape {
-    //     FormatInlineShape {
-    //         shape: self,
-    //         column: Some(column.into()),
-    //     }
-    // }
+    #[allow(unused)]
+    pub fn format_for_column(self, column: impl Into<Column>) -> FormatInlineShape {
+        FormatInlineShape {
+            shape: self,
+            column: Some(column.into()),
+        }
+    }
 
     pub fn format(self) -> FormatInlineShape {
         FormatInlineShape {
@@ -298,7 +300,7 @@ impl InlineShape {
 }
 
 impl PrettyDebug for FormatInlineShape {
-    fn pretty_debug(&self) -> DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
         let column = &self.column;
 
         match &self.shape {
@@ -323,10 +325,9 @@ impl PrettyDebug for FormatInlineShape {
                 }
             }
             InlineShape::String(string) => b::primitive(format!("{}", string)),
-            InlineShape::ColumnPath(path) => b::intersperse(
-                path.iter().map(|member| member.pretty_debug()),
-                b::keyword("."),
-            ),
+            InlineShape::ColumnPath(path) => {
+                b::intersperse(path.iter().map(|member| member.pretty()), b::keyword("."))
+            }
             InlineShape::Pattern(pattern) => b::primitive(pattern),
             InlineShape::Boolean(boolean) => b::primitive(match (boolean, column) {
                 (true, None) => format!("Yes"),
@@ -485,15 +486,15 @@ impl Value {
 
 impl Shape {
     pub fn for_value(value: &Value) -> Shape {
-        match value {
-            Value::Primitive(p) => Shape::Primitive(p.type_name()),
-            Value::Row(row) => Shape::for_dict(row),
-            Value::Table(table) => Shape::Table {
+        match &value.value {
+            UntaggedValue::Primitive(p) => Shape::Primitive(p.type_name()),
+            UntaggedValue::Row(row) => Shape::for_dict(row),
+            UntaggedValue::Table(table) => Shape::Table {
                 from: 0,
                 to: table.len(),
             },
-            Value::Error(error) => Shape::Error(error.clone()),
-            Value::Block(block) => Shape::Block(block.clone()),
+            UntaggedValue::Error(error) => Shape::Error(error.clone()),
+            UntaggedValue::Block(block) => Shape::Block(block.clone()),
         }
     }
 
@@ -558,7 +559,7 @@ impl Shape {
             .expect("Writing into a Vec can't fail");
         let string = String::from_utf8_lossy(&out);
 
-        Value::string(string)
+        UntaggedValue::string(string).into_untagged_value()
     }
 }
 
@@ -582,13 +583,13 @@ impl Shapes {
             .or_insert_with(|| vec![row]);
     }
 
-    pub fn to_values(&self) -> Vec<Tagged<Value>> {
+    pub fn to_values(&self) -> Vec<Value> {
         if self.shapes.len() == 1 {
             let shape = self.shapes.keys().nth(0).unwrap();
 
             vec![dict! {
                 "type" => shape.to_value(),
-                "rows" => Value::string("all")
+                "rows" => UntaggedValue::string("all")
             }]
         } else {
             self.shapes
@@ -598,7 +599,7 @@ impl Shapes {
 
                     dict! {
                         "type" => shape.to_value(),
-                        "rows" => Value::string(format!("[ {} ]", rows))
+                        "rows" => UntaggedValue::string(format!("[ {} ]", rows))
                     }
                 })
                 .collect()

src/data/command.rs

@@ -4,43 +4,43 @@ use crate::parser::registry::{NamedType, PositionalType, Signature};
 use crate::prelude::*;
 use std::ops::Deref;
 
-pub(crate) fn command_dict(command: Arc<Command>, tag: impl Into<Tag>) -> Tagged<Value> {
+pub(crate) fn command_dict(command: Arc<Command>, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     let mut cmd_dict = TaggedDictBuilder::new(&tag);
 
-    cmd_dict.insert("name", Value::string(command.name()));
+    cmd_dict.insert_untagged("name", UntaggedValue::string(command.name()));
 
-    cmd_dict.insert(
+    cmd_dict.insert_untagged(
         "type",
-        Value::string(match command.deref() {
+        UntaggedValue::string(match command.deref() {
             Command::WholeStream(_) => "Command",
             Command::PerItem(_) => "Filter",
         }),
     );
 
-    cmd_dict.insert_tagged("signature", signature_dict(command.signature(), tag));
-    cmd_dict.insert("usage", Value::string(command.usage()));
+    cmd_dict.insert_value("signature", signature_dict(command.signature(), tag));
+    cmd_dict.insert_untagged("usage", UntaggedValue::string(command.usage()));
 
-    cmd_dict.into_tagged_value()
+    cmd_dict.into_value()
 }
 
-fn for_spec(name: &str, ty: &str, required: bool, tag: impl Into<Tag>) -> Tagged<Value> {
+fn for_spec(name: &str, ty: &str, required: bool, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
 
     let mut spec = TaggedDictBuilder::new(tag);
 
-    spec.insert("name", Value::string(name));
-    spec.insert("type", Value::string(ty));
-    spec.insert(
+    spec.insert_untagged("name", UntaggedValue::string(name));
+    spec.insert_untagged("type", UntaggedValue::string(ty));
+    spec.insert_untagged(
         "required",
-        Value::string(if required { "yes" } else { "no" }),
+        UntaggedValue::string(if required { "yes" } else { "no" }),
     );
 
-    spec.into_tagged_value()
+    spec.into_value()
 }
 
-fn signature_dict(signature: Signature, tag: impl Into<Tag>) -> Tagged<Value> {
+fn signature_dict(signature: Signature, tag: impl Into<Tag>) -> Value {
     let tag = tag.into();
     let mut sig = TaggedListBuilder::new(&tag);
 
@@ -50,21 +50,21 @@ fn signature_dict(signature: Signature, tag: impl Into<Tag>) -> Tagged<Value> {
             PositionalType::Optional(_, _) => false,
         };
 
-        sig.insert_tagged(for_spec(arg.0.name(), "argument", is_required, &tag));
+        sig.push_value(for_spec(arg.0.name(), "argument", is_required, &tag));
     }
 
     if let Some(_) = signature.rest_positional {
         let is_required = false;
-        sig.insert_tagged(for_spec("rest", "argument", is_required, &tag));
+        sig.push_value(for_spec("rest", "argument", is_required, &tag));
     }
 
     for (name, ty) in signature.named.iter() {
         match ty.0 {
-            NamedType::Mandatory(_) => sig.insert_tagged(for_spec(name, "flag", true, &tag)),
-            NamedType::Optional(_) => sig.insert_tagged(for_spec(name, "flag", false, &tag)),
-            NamedType::Switch => sig.insert_tagged(for_spec(name, "switch", false, &tag)),
+            NamedType::Mandatory(_) => sig.push_value(for_spec(name, "flag", true, &tag)),
+            NamedType::Optional(_) => sig.push_value(for_spec(name, "flag", false, &tag)),
+            NamedType::Switch => sig.push_value(for_spec(name, "switch", false, &tag)),
         }
     }
 
-    sig.into_tagged_value()
+    sig.into_value()
 }

src/data/config.rs

@@ -14,7 +14,7 @@ use std::path::{Path, PathBuf};
 #[derive(Deserialize, Serialize)]
 struct Config {
     #[serde(flatten)]
-    extra: IndexMap<String, Tagged<Value>>,
+    extra: IndexMap<String, Value>,
 }
 
 pub const APP_INFO: AppInfo = AppInfo {
@@ -61,7 +61,7 @@ pub fn app_path(app_data_type: AppDataType, display: &str) -> Result<PathBuf, Sh
 pub fn read(
     tag: impl Into<Tag>,
     at: &Option<PathBuf>,
-) -> Result<IndexMap<String, Tagged<Value>>, ShellError> {
+) -> Result<IndexMap<String, Value>, ShellError> {
     let filename = default_path()?;
 
     let filename = match at {
@@ -94,8 +94,8 @@ pub fn read(
 
     let value = convert_toml_value_to_nu_value(&parsed, tag);
     let tag = value.tag();
-    match value.item {
-        Value::Row(Dictionary { entries }) => Ok(entries),
+    match value.value {
+        UntaggedValue::Row(Dictionary { entries }) => Ok(entries),
         other => Err(ShellError::type_error(
             "Dictionary",
             other.type_name().spanned(tag.span),
@@ -103,14 +103,11 @@ pub fn read(
     }
 }
 
-pub(crate) fn config(tag: impl Into<Tag>) -> Result<IndexMap<String, Tagged<Value>>, ShellError> {
+pub(crate) fn config(tag: impl Into<Tag>) -> Result<IndexMap<String, Value>, ShellError> {
     read(tag, &None)
 }
 
-pub fn write(
-    config: &IndexMap<String, Tagged<Value>>,
-    at: &Option<PathBuf>,
-) -> Result<(), ShellError> {
+pub fn write(config: &IndexMap<String, Value>, at: &Option<PathBuf>) -> Result<(), ShellError> {
     let filename = &mut default_path()?;
     let filename = match at {
         None => filename,
@@ -121,8 +118,9 @@ pub fn write(
         }
     };
 
-    let contents =
-        value_to_toml_value(&Value::Row(Dictionary::new(config.clone())).tagged_unknown())?;
+    let contents = value_to_toml_value(
+        &UntaggedValue::Row(Dictionary::new(config.clone())).into_untagged_value(),
+    )?;
 
     let contents = toml::to_string(&contents)?;
 

src/data/dict.rs

@@ -1,9 +1,10 @@
-use crate::data::{Primitive, Value};
+use crate::data::base::{Primitive, UntaggedValue, Value};
 use crate::prelude::*;
-use crate::traits::{DebugDocBuilder as b, PrettyDebug};
 use derive_new::new;
 use getset::Getters;
 use indexmap::IndexMap;
+use nu_source::Spanned;
+use nu_source::{b, PrettyDebug};
 use pretty::{BoxAllocator, DocAllocator};
 use serde::{Deserialize, Serialize};
 use std::cmp::{Ordering, PartialOrd};
@@ -11,41 +12,23 @@ use std::cmp::{Ordering, PartialOrd};
 #[derive(Debug, Default, Eq, PartialEq, Serialize, Deserialize, Clone, Getters, new)]
 pub struct Dictionary {
     #[get = "pub"]
-    pub entries: IndexMap<String, Tagged<Value>>,
+    pub entries: IndexMap<String, Value>,
 }
 
 #[derive(Debug, new)]
 struct DebugEntry<'a> {
     key: &'a str,
-    value: &'a Tagged<Value>,
+    value: &'a Value,
 }
 
 impl<'a> PrettyDebug for DebugEntry<'a> {
-    fn pretty_debug(&self) -> DebugDocBuilder {
-        (b::key(self.key.to_string()) + b::equals() + self.value.item.pretty_debug().as_value())
-            .group()
-        // BoxAllocator
-        //     .text(self.key.to_string())
-        //     .annotate(ShellAnnotation::style("key"))
-        //     .append(
-        //         BoxAllocator
-        //             .text("=")
-        //             .annotate(ShellAnnotation::style("equals")),
-        //     )
-        //     .append({
-        //         self.value
-        //             .item
-        //             .pretty_debug()
-        //             .inner
-        //             .annotate(ShellAnnotation::style("value"))
-        //     })
-        //     .group()
-        //     .into()
+    fn pretty(&self) -> DebugDocBuilder {
+        (b::key(self.key.to_string()) + b::equals() + self.value.pretty().as_value()).group()
     }
 }
 
 impl PrettyDebug for Dictionary {
-    fn pretty_debug(&self) -> DebugDocBuilder {
+    fn pretty(&self) -> DebugDocBuilder {
         BoxAllocator
             .text("(")
             .append(
@@ -73,15 +56,15 @@ impl PartialOrd for Dictionary {
             return this.partial_cmp(&that);
         }
 
-        let this: Vec<&Value> = self.entries.values().map(|v| v.item()).collect();
-        let that: Vec<&Value> = self.entries.values().map(|v| v.item()).collect();
+        let this: Vec<&Value> = self.entries.values().collect();
+        let that: Vec<&Value> = self.entries.values().collect();
 
         this.partial_cmp(&that)
     }
 }
 
-impl From<IndexMap<String, Tagged<Value>>> for Dictionary {
-    fn from(input: IndexMap<String, Tagged<Value>>) -> Dictionary {
+impl From<IndexMap<String, Value>> for Dictionary {
+    fn from(input: IndexMap<String, Value>) -> Dictionary {
         let mut out = IndexMap::default();
 
         for (key, value) in input {
@@ -101,8 +84,8 @@ impl Ord for Dictionary {
             return this.cmp(&that);
         }
 
-        let this: Vec<&Value> = self.entries.values().map(|v| v.item()).collect();
-        let that: Vec<&Value> = self.entries.values().map(|v| v.item()).collect();
+        let this: Vec<&Value> = self.entries.values().collect();
+        let that: Vec<&Value> = self.entries.values().collect();
 
         this.cmp(&that)
     }
@@ -116,8 +99,8 @@ impl PartialOrd<Value> for Dictionary {
 
 impl PartialEq<Value> for Dictionary {
     fn eq(&self, other: &Value) -> bool {
-        match other {
-            Value::Row(d) => self == d,
+        match &other.value {
+            UntaggedValue::Row(d) => self == d,
             _ => false,
         }
     }
@@ -127,7 +110,9 @@ impl Dictionary {
     pub fn get_data(&self, desc: &String) -> MaybeOwned<'_, Value> {
         match self.entries.get(desc) {
             Some(v) => MaybeOwned::Borrowed(v),
-            None => MaybeOwned::Owned(Value::Primitive(Primitive::Nothing)),
+            None => MaybeOwned::Owned(
+                UntaggedValue::Primitive(Primitive::Nothing).into_untagged_value(),
+            ),
         }
     }
 
@@ -135,7 +120,7 @@ impl Dictionary {
         self.entries.keys()
     }
 
-    pub(crate) fn get_data_by_key(&self, name: Spanned<&str>) -> Option<Tagged<Value>> {
+    pub(crate) fn get_data_by_key(&self, name: Spanned<&str>) -> Option<Value> {
         let result = self
             .entries
             .iter()
@@ -144,13 +129,13 @@ impl Dictionary {
 
         Some(
             result
-                .item
+                .value
                 .clone()
-                .tagged(Tag::new(result.anchor(), name.span)),
+                .into_value(Tag::new(result.anchor(), name.span)),
         )
     }
 
-    pub(crate) fn get_mut_data_by_key(&mut self, name: &str) -> Option<&mut Tagged<Value>> {
+    pub(crate) fn get_mut_data_by_key(&mut self, name: &str) -> Option<&mut Value> {
         match self
             .entries
             .iter_mut()
@@ -161,7 +146,7 @@ impl Dictionary {
         }
     }
 
-    pub(crate) fn insert_data_at_key(&mut self, name: &str, value: Tagged<Value>) {
+    pub(crate) fn insert_data_at_key(&mut self, name: &str, value: Value) {
         self.entries.insert(name.to_string(), value);
     }
 }
@@ -169,7 +154,7 @@ impl Dictionary {
 #[derive(Debug)]
 pub struct TaggedListBuilder {
     tag: Tag,
-    pub list: Vec<Tagged<Value>>,
+    pub list: Vec<Value>,
 }
 
 impl TaggedListBuilder {
@@ -180,29 +165,33 @@ impl TaggedListBuilder {
         }
     }
 
-    pub fn push(&mut self, value: impl Into<Value>) {
-        self.list.push(value.into().tagged(&self.tag));
-    }
-
-    pub fn insert_tagged(&mut self, value: impl Into<Tagged<Value>>) {
+    pub fn push_value(&mut self, value: impl Into<Value>) {
         self.list.push(value.into());
     }
 
-    pub fn into_tagged_value(self) -> Tagged<Value> {
-        Value::Table(self.list).tagged(self.tag)
+    pub fn push_untagged(&mut self, value: impl Into<UntaggedValue>) {
+        self.list.push(value.into().into_value(self.tag.clone()));
+    }
+
+    pub fn into_value(self) -> Value {
+        UntaggedValue::Table(self.list).into_value(self.tag)
+    }
+
+    pub fn into_untagged_value(self) -> UntaggedValue {
+        UntaggedValue::Table(self.list).into_value(self.tag).value
     }
 }
 
-impl From<TaggedListBuilder> for Tagged<Value> {
-    fn from(input: TaggedListBuilder) -> Tagged<Value> {
-        input.into_tagged_value()
+impl From<TaggedListBuilder> for Value {
+    fn from(input: TaggedListBuilder) -> Value {
+        input.into_value()
     }
 }
 
 #[derive(Debug)]
 pub struct TaggedDictBuilder {
     tag: Tag,
-    dict: IndexMap<String, Tagged<Value>>,
+    dict: IndexMap<String, Value>,
 }
 
 impl TaggedDictBuilder {
@@ -213,10 +202,10 @@ impl TaggedDictBuilder {
         }
     }
 
-    pub fn build(tag: impl Into<Tag>, block: impl FnOnce(&mut TaggedDictBuilder)) -> Tagged<Value> {
+    pub fn build(tag: impl Into<Tag>, block: impl FnOnce(&mut TaggedDictBuilder)) -> Value {
         let mut builder = TaggedDictBuilder::new(tag);
         block(&mut builder);
-        builder.into_tagged_value()
+        builder.into_value()
     }
 
     pub fn with_capacity(tag: impl Into<Tag>, n: usize) -> TaggedDictBuilder {
@@ -226,20 +215,22 @@ impl TaggedDictBuilder {
         }
     }
 
-    pub fn insert(&mut self, key: impl Into<String>, value: impl Into<Value>) {
-        self.dict.insert(key.into(), value.into().tagged(&self.tag));
+    pub fn insert_untagged(&mut self, key: impl Into<String>, value: impl Into<UntaggedValue>) {
+        self.dict
+            .insert(key.into(), value.into().into_value(&self.tag));
     }
 
-    pub fn insert_tagged(&mut self, key: impl Into<String>, value: impl Into<Tagged<Value>>) {
+    pub fn insert_value(&mut self, key: impl Into<String>, value: impl Into<Value>) {
         self.dict.insert(key.into(), value.into());
     }
 
-    pub fn into_tagged_value(self) -> Tagged<Value> {
-        self.into_tagged_dict().map(Value::Row)
+    pub fn into_value(self) -> Value {
+        let tag = self.tag.clone();
+        self.into_untagged_value().into_value(tag)
     }
 
-    pub fn into_tagged_dict(self) -> Tagged<Dictionary> {
-        Dictionary { entries: self.dict }.tagged(self.tag)
+    pub fn into_untagged_value(self) -> UntaggedValue {
+        UntaggedValue::Row(Dictionary { entries: self.dict })
     }
 
     pub fn is_empty(&self) -> bool {
@@ -247,8 +238,8 @@ impl TaggedDictBuilder {
     }
 }
 
-impl From<TaggedDictBuilder> for Tagged<Value> {
-    fn from(input: TaggedDictBuilder) -> Tagged<Value> {
-        input.into_tagged_value()
+impl From<TaggedDictBuilder> for Value {
+    fn from(input: TaggedDictBuilder) -> Value {
+        input.into_value()
     }
 }

src/data/files.rs

@@ -14,9 +14,9 @@ pub(crate) fn dir_entry_dict(
     metadata: &std::fs::Metadata,
     tag: impl Into<Tag>,
     full: bool,
-) -> Result<Tagged<Value>, ShellError> {
+) -> Result<Value, ShellError> {
     let mut dict = TaggedDictBuilder::new(tag);
-    dict.insert("name", Value::string(filename.to_string_lossy()));
+    dict.insert_untagged("name", UntaggedValue::string(filename.to_string_lossy()));
 
     let kind = if metadata.is_dir() {
         FileType::Directory
@@ -26,38 +26,41 @@ pub(crate) fn dir_entry_dict(
         FileType::Symlink
     };
 
-    dict.insert("type", Value::string(format!("{:?}", kind)));
+    dict.insert_untagged("type", UntaggedValue::string(format!("{:?}", kind)));
 
     if full {
-        dict.insert(
+        dict.insert_untagged(
             "readonly",
-            Value::boolean(metadata.permissions().readonly()),
+            UntaggedValue::boolean(metadata.permissions().readonly()),
         );
 
         #[cfg(unix)]
         {
             use std::os::unix::fs::PermissionsExt;
             let mode = metadata.permissions().mode();
-            dict.insert("mode", Value::string(umask::Mode::from(mode).to_string()));
+            dict.insert(
+                "mode",
+                UntaggedValue::string(umask::Mode::from(mode).to_string()),
+            );
         }
     }
 
-    dict.insert("size", Value::bytes(metadata.len() as u64));
+    dict.insert_untagged("size", UntaggedValue::bytes(metadata.len() as u64));
 
     match metadata.created() {
-        Ok(c) => dict.insert("created", Value::system_date(c)),
+        Ok(c) => dict.insert_untagged("created", UntaggedValue::system_date(c)),
         Err(_) => {}
     }
 
     match metadata.accessed() {
-        Ok(a) => dict.insert("accessed", Value::system_date(a)),
+        Ok(a) => dict.insert_untagged("accessed", UntaggedValue::system_date(a)),
         Err(_) => {}
     }
 
     match metadata.modified() {
-        Ok(m) => dict.insert("modified", Value::system_date(m)),
+        Ok(m) => dict.insert_untagged("modified", UntaggedValue::system_date(m)),
         Err(_) => {}
     }
 
-    Ok(dict.into_tagged_value())
+    Ok(dict.into_value())
 }

src/data/into.rs

@@ -1,22 +1,13 @@
-use crate::data::{Primitive, Value};
-use crate::prelude::*;
+use crate::data::base::{Primitive, UntaggedValue};
 
-impl From<Primitive> for Value {
-    fn from(input: Primitive) -> Value {
-        Value::Primitive(input)
+impl From<Primitive> for UntaggedValue {
+    fn from(input: Primitive) -> UntaggedValue {
+        UntaggedValue::Primitive(input)
     }
 }
 
-impl From<String> for Value {
-    fn from(input: String) -> Value {
-        Value::Primitive(Primitive::String(input))
-    }
-}
-
-impl<T: Into<Value>> Tagged<T> {
-    pub fn into_tagged_value(self) -> Tagged<Value> {
-        let value_tag = self.tag();
-        let value = self.item.into();
-        value.tagged(value_tag)
+impl From<String> for UntaggedValue {
+    fn from(input: String) -> UntaggedValue {
+        UntaggedValue::Primitive(Primitive::String(input))
     }
 }

src/data/process.rs

@@ -3,27 +3,27 @@ use crate::prelude::*;
 use itertools::join;
 use sysinfo::ProcessExt;
 
-pub(crate) fn process_dict(proc: &sysinfo::Process, tag: impl Into<Tag>) -> Tagged<Value> {
+pub(crate) fn process_dict(proc: &sysinfo::Process, tag: impl Into<Tag>) -> Value {
     let mut dict = TaggedDictBuilder::new(tag);
 
     let cmd = proc.cmd();
 
     let cmd_value = if cmd.len() == 0 {
-        Value::nothing()
+        UntaggedValue::nothing()
     } else {
-        Value::string(join(cmd, ""))
+        UntaggedValue::string(join(cmd, ""))
     };
 
-    dict.insert("pid", Value::int(proc.pid() as i64));
-    dict.insert("status", Value::string(proc.status().to_string()));
-    dict.insert("cpu", Value::number(proc.cpu_usage()));
+    dict.insert("pid", UntaggedValue::int(proc.pid() as i64));
+    dict.insert("status", UntaggedValue::string(proc.status().to_string()));
+    dict.insert("cpu", UntaggedValue::number(proc.cpu_usage()));
 
     match cmd_value {
-        Value::Primitive(Primitive::Nothing) => {
-            dict.insert("name", Value::string(proc.name()));
+        UntaggedValue::Primitive(Primitive::Nothing) => {
+            dict.insert("name", UntaggedValue::string(proc.name()));
         }
         _ => dict.insert("name", cmd_value),
     }
 
-    dict.into_tagged_value()
+    dict.into_value()
 }

src/data/types.rs

@@ -1,12 +1,13 @@
 use crate::prelude::*;
 use log::trace;
+use nu_source::Tagged;
 
 pub trait ExtractType: Sized {
-    fn extract(value: &Tagged<Value>) -> Result<Self, ShellError>;
+    fn extract(value: &Value) -> Result<Self, ShellError>;
 }
 
 impl<T: ExtractType> ExtractType for Tagged<T> {
-    fn extract(value: &Tagged<Value>) -> Result<Tagged<T>, ShellError> {
+    fn extract(value: &Value) -> Result<Tagged<T>, ShellError> {
         let name = std::any::type_name::<T>();
         trace!("<Tagged> Extracting {:?} for Tagged<{}>", value, name);
 
@@ -15,16 +16,16 @@ impl<T: ExtractType> ExtractType for Tagged<T> {
 }
 
 impl ExtractType for bool {
-    fn extract(value: &Tagged<Value>) -> Result<bool, ShellError> {
+    fn extract(value: &Value) -> Result<bool, ShellError> {
         trace!("Extracting {:?} for bool", value);
 
         match &value {
-            Tagged {
-                item: Value::Primitive(Primitive::Boolean(b)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Boolean(b)),
                 ..
             } => Ok(*b),
-            Tagged {
-                item: Value::Primitive(Primitive::Nothing),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Nothing),
                 ..
             } => Ok(false),
             other => Err(ShellError::type_error(
@@ -36,12 +37,12 @@ impl ExtractType for bool {
 }
 
 impl ExtractType for std::path::PathBuf {
-    fn extract(value: &Tagged<Value>) -> Result<std::path::PathBuf, ShellError> {
+    fn extract(value: &Value) -> Result<std::path::PathBuf, ShellError> {
         trace!("Extracting {:?} for PathBuf", value);
 
         match &value {
-            Tagged {
-                item: Value::Primitive(Primitive::Path(p)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Path(p)),
                 ..
             } => Ok(p.clone()),
             other => Err(ShellError::type_error(
@@ -53,12 +54,12 @@ impl ExtractType for std::path::PathBuf {
 }
 
 impl ExtractType for i64 {
-    fn extract(value: &Tagged<Value>) -> Result<i64, ShellError> {
+    fn extract(value: &Value) -> Result<i64, ShellError> {
         trace!("Extracting {:?} for i64", value);
 
         match &value {
-            &Tagged {
-                item: Value::Primitive(Primitive::Int(int)),
+            &Value {
+                value: UntaggedValue::Primitive(Primitive::Int(int)),
                 ..
             } => Ok(int.tagged(&value.tag).coerce_into("converting to i64")?),
             other => Err(ShellError::type_error(
@@ -70,12 +71,12 @@ impl ExtractType for i64 {
 }
 
 impl ExtractType for u64 {
-    fn extract(value: &Tagged<Value>) -> Result<u64, ShellError> {
+    fn extract(value: &Value) -> Result<u64, ShellError> {
         trace!("Extracting {:?} for u64", value);
 
         match &value {
-            &Tagged {
-                item: Value::Primitive(Primitive::Int(int)),
+            &Value {
+                value: UntaggedValue::Primitive(Primitive::Int(int)),
                 ..
             } => Ok(int.tagged(&value.tag).coerce_into("converting to u64")?),
             other => Err(ShellError::type_error(
@@ -87,12 +88,12 @@ impl ExtractType for u64 {
 }
 
 impl ExtractType for String {
-    fn extract(value: &Tagged<Value>) -> Result<String, ShellError> {
+    fn extract(value: &Value) -> Result<String, ShellError> {
         trace!("Extracting {:?} for String", value);
 
         match value {
-            Tagged {
-                item: Value::Primitive(Primitive::String(string)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::String(string)),
                 ..
             } => Ok(string.clone()),
             other => Err(ShellError::type_error(

src/errors.rs

@@ -1,29 +1,29 @@
 use crate::prelude::*;
 
-use crate::parser::parse::parser::TracableContext;
 use ansi_term::Color;
 use derive_new::new;
 use language_reporting::{Diagnostic, Label, Severity};
+use nu_source::{Spanned, TracableContext};
 use serde::{Deserialize, Serialize};
 use std::fmt;
 use std::ops::Range;
 
+// TODO: Spanned<T> -> HasSpanAndItem<T> ?
+
 #[derive(Debug, Eq, PartialEq, Clone, Ord, PartialOrd, Hash, Serialize, Deserialize)]
 pub enum Description {
     Source(Spanned<String>),
     Synthetic(String),
 }
 
-impl<T: Into<String>> Into<Description> for Spanned<T> {
-    fn into(self) -> Description {
-        Description::Source(self.map(|s| s.into()))
-    }
-}
-
 impl Description {
+    fn from_spanned(item: Spanned<impl Into<String>>) -> Description {
+        Description::Source(item.map(|s| s.into()))
+    }
+
     fn into_label(self) -> Result<Label<Span>, String> {
         match self {
-            Description::Source(s) => Ok(Label::new_primary(s.span()).with_message(s.item)),
+            Description::Source(s) => Ok(Label::new_primary(s.span).with_message(s.item)),
             Description::Synthetic(s) => Err(s),
         }
     }
@@ -106,12 +106,6 @@ pub struct ShellError {
     cause: Option<Box<ProximateShellError>>,
 }
 
-impl FormatDebug for ShellError {
-    fn fmt_debug(&self, f: &mut DebugFormatter, source: &str) -> fmt::Result {
-        self.error.fmt_debug(f, source)
-    }
-}
-
 impl serde::de::Error for ShellError {
     fn custom<T>(msg: T) -> Self
     where
@@ -138,8 +132,8 @@ impl ShellError {
         expr: Spanned<impl Into<String>>,
     ) -> ShellError {
         ProximateShellError::MissingProperty {
-            subpath: subpath.into(),
-            expr: expr.into(),
+            subpath: Description::from_spanned(subpath),
+            expr: Description::from_spanned(expr),
         }
         .start()
     }
@@ -149,7 +143,7 @@ impl ShellError {
         integer: impl Into<Span>,
     ) -> ShellError {
         ProximateShellError::InvalidIntegerIndex {
-            subpath: subpath.into(),
+            subpath: Description::from_spanned(subpath),
             integer: integer.into(),
         }
         .start()
@@ -172,12 +166,12 @@ impl ShellError {
 
     pub(crate) fn range_error(
         expected: impl Into<ExpectedRange>,
-        actual: &Tagged<impl fmt::Debug>,
+        actual: &Spanned<impl fmt::Debug>,
         operation: impl Into<String>,
     ) -> ShellError {
         ProximateShellError::RangeError {
             kind: expected.into(),
-            actual_kind: format!("{:?}", actual.item).spanned(actual.span()),
+            actual_kind: format!("{:?}", actual.item).spanned(actual.span),
             operation: operation.into(),
         }
         .start()
@@ -201,14 +195,6 @@ impl ShellError {
         .start()
     }
 
-    pub(crate) fn missing_value(span: Option<Span>, reason: impl Into<String>) -> ShellError {
-        ProximateShellError::MissingValue {
-            span,
-            reason: reason.into(),
-        }
-        .start()
-    }
-
     pub(crate) fn argument_error(
         command: Spanned<impl Into<String>>,
         kind: ArgumentError,
@@ -404,28 +390,28 @@ impl ShellError {
     pub fn labeled_error(
         msg: impl Into<String>,
         label: impl Into<String>,
-        tag: impl Into<Tag>,
+        span: impl Into<Span>,
     ) -> ShellError {
         ShellError::diagnostic(
             Diagnostic::new(Severity::Error, msg.into())
-                .with_label(Label::new_primary(tag.into().span).with_message(label.into())),
+                .with_label(Label::new_primary(span.into()).with_message(label.into())),
         )
     }
 
     pub fn labeled_error_with_secondary(
         msg: impl Into<String>,
         primary_label: impl Into<String>,
-        primary_span: impl Into<Tag>,
+        primary_span: impl Into<Span>,
         secondary_label: impl Into<String>,
-        secondary_span: impl Into<Tag>,
+        secondary_span: impl Into<Span>,
     ) -> ShellError {
         ShellError::diagnostic(
             Diagnostic::new_error(msg.into())
                 .with_label(
-                    Label::new_primary(primary_span.into().span).with_message(primary_label.into()),
+                    Label::new_primary(primary_span.into()).with_message(primary_label.into()),
                 )
                 .with_label(
-                    Label::new_secondary(secondary_span.into().span)
+                    Label::new_secondary(secondary_span.into())
                         .with_message(secondary_label.into()),
                 ),
         )
@@ -573,13 +559,6 @@ impl ProximateShellError {
     // }
 }
 
-impl FormatDebug for ProximateShellError {
-    fn fmt_debug(&self, f: &mut DebugFormatter, _source: &str) -> fmt::Result {
-        // TODO: Custom debug for inner spans
-        write!(f, "{:?}", self)
-    }
-}
-
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ShellDiagnostic {
     pub(crate) diagnostic: Diagnostic<Span>,
@@ -690,18 +669,6 @@ impl std::convert::From<Box<dyn std::error::Error + Send + Sync>> for ShellError
     }
 }
 
-pub trait ShellErrorUtils<T> {
-    fn unwrap_error(self, desc: impl Into<String>) -> Result<T, ShellError>;
-}
-
-impl<T> ShellErrorUtils<Tagged<T>> for Option<Tagged<T>> {
-    fn unwrap_error(self, desc: impl Into<String>) -> Result<Tagged<T>, ShellError> {
-        match self {
-            Some(value) => Ok(value),
-            None => Err(ShellError::missing_value(None, desc.into())),
-        }
-    }
-}
 pub trait CoerceInto<U> {
     fn coerce_into(self, operation: impl Into<String>) -> Result<U, ShellError>;
 }
@@ -718,26 +685,26 @@ macro_rules! ranged_int {
             }
         }
 
-        impl CoerceInto<$ty> for Tagged<BigInt> {
+        impl CoerceInto<$ty> for nu_source::Tagged<BigInt> {
             fn coerce_into(self, operation: impl Into<String>) -> Result<$ty, ShellError> {
                 match self.$op() {
                     Some(v) => Ok(v),
                     None => Err(ShellError::range_error(
                         $ty::to_expected_range(),
-                        &self,
+                        &self.item.spanned(self.tag.span),
                         operation.into(),
                     )),
                 }
             }
         }
 
-        impl CoerceInto<$ty> for Tagged<&BigInt> {
+        impl CoerceInto<$ty> for nu_source::Tagged<&BigInt> {
             fn coerce_into(self, operation: impl Into<String>) -> Result<$ty, ShellError> {
                 match self.$op() {
                     Some(v) => Ok(v),
                     None => Err(ShellError::range_error(
                         $ty::to_expected_range(),
-                        &self,
+                        &self.item.spanned(self.tag.span),
                         operation.into(),
                     )),
                 }
@@ -763,26 +730,26 @@ macro_rules! ranged_decimal {
             }
         }
 
-        impl CoerceInto<$ty> for Tagged<BigDecimal> {
+        impl CoerceInto<$ty> for nu_source::Tagged<BigDecimal> {
             fn coerce_into(self, operation: impl Into<String>) -> Result<$ty, ShellError> {
                 match self.$op() {
                     Some(v) => Ok(v),
                     None => Err(ShellError::range_error(
                         $ty::to_expected_range(),
-                        &self,
+                        &self.item.spanned(self.tag.span),
                         operation.into(),
                     )),
                 }
             }
         }
 
-        impl CoerceInto<$ty> for Tagged<&BigDecimal> {
+        impl CoerceInto<$ty> for nu_source::Tagged<&BigDecimal> {
             fn coerce_into(self, operation: impl Into<String>) -> Result<$ty, ShellError> {
                 match self.$op() {
                     Some(v) => Ok(v),
                     None => Err(ShellError::range_error(
                         $ty::to_expected_range(),
-                        &self,
+                        &self.item.spanned(self.tag.span),
                         operation.into(),
                     )),
                 }