Removing async_stream! from some commands (#1940)

* Removing async_stream! from some commands

* Revert row.rs code

* Simplify logic for first.rs and skip.rs

crates/nu-cli/src/commands/first.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 
 pub struct First;
@@ -35,7 +35,7 @@ impl WholeStreamCommand for First {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        first(args, registry)
+        first(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -57,27 +57,16 @@ impl WholeStreamCommand for First {
     }
 }
 
-fn first(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn first(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let (FirstArgs { rows }, mut input) = args.process(&registry).await?;
-        let mut rows_desired = if let Some(quantity) = rows {
-            *quantity
-        } else {
-            1
-        };
-
-        while let Some(input) = input.next().await {
-            if rows_desired > 0 {
-                yield ReturnSuccess::value(input);
-                rows_desired -= 1;
-            } else {
-                break;
-            }
-        }
+    let (FirstArgs { rows }, input) = args.process(&registry).await?;
+    let rows_desired = if let Some(quantity) = rows {
+        *quantity
+    } else {
+        1
     };
 
-    Ok(stream.to_output_stream())
+    Ok(input.take(rows_desired).to_output_stream())
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_bson.rs

@@ -27,7 +27,7 @@ impl WholeStreamCommand for FromBSON {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_bson(args, registry)
+        from_bson(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -208,30 +208,27 @@ pub fn from_bson_bytes_to_value(bytes: Vec<u8>, tag: impl Into<Tag>) -> Result<V
     convert_bson_value_to_nu_value(&Bson::Array(docs), tag)
 }
 
-fn from_bson(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_bson(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
 
-        let bytes = input.collect_binary(tag.clone()).await?;
+    let bytes = input.collect_binary(tag.clone()).await?;
 
-        match from_bson_bytes_to_value(bytes.item, tag.clone()) {
-            Ok(x) => yield ReturnSuccess::value(x),
-            Err(_) => {
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "Could not parse as BSON",
-                    "input cannot be parsed as BSON",
-                    tag.clone(),
-                    "value originates from here",
-                    bytes.tag,
-                ))
-            }
-        }
-    };
-
-    Ok(stream.to_output_stream())
+    match from_bson_bytes_to_value(bytes.item, tag.clone()) {
+        Ok(x) => Ok(OutputStream::one(ReturnSuccess::value(x))),
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
+            "Could not parse as BSON",
+            "input cannot be parsed as BSON",
+            tag.clone(),
+            "value originates from here",
+            bytes.tag,
+        )),
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_csv.rs

@@ -42,7 +42,7 @@ impl WholeStreamCommand for FromCSV {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_csv(args, registry)
+        from_csv(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -66,43 +66,44 @@ impl WholeStreamCommand for FromCSV {
     }
 }
 
-fn from_csv(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_csv(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
     let name = args.call_info.name_tag.clone();
-    let stream = async_stream! {
-        let (FromCSVArgs { headerless, separator }, mut input) = args.process(&registry).await?;
-        let sep = match separator {
-            Some(Value {
-                value: UntaggedValue::Primitive(Primitive::String(s)),
-                tag,
-                ..
-            }) => {
-                if s == r"\t" {
-                    '\t'
-                } else {
-                    let vec_s: Vec<char> = s.chars().collect();
-                    if vec_s.len() != 1 {
-                        yield Err(ShellError::labeled_error(
-                            "Expected a single separator char from --separator",
-                            "requires a single character string input",
-                            tag,
-                        ));
-                        return;
-                    };
-                    vec_s[0]
-                }
+
+    let (
+        FromCSVArgs {
+            headerless,
+            separator,
+        },
+        input,
+    ) = args.process(&registry).await?;
+    let sep = match separator {
+        Some(Value {
+            value: UntaggedValue::Primitive(Primitive::String(s)),
+            tag,
+            ..
+        }) => {
+            if s == r"\t" {
+                '\t'
+            } else {
+                let vec_s: Vec<char> = s.chars().collect();
+                if vec_s.len() != 1 {
+                    return Err(ShellError::labeled_error(
+                        "Expected a single separator char from --separator",
+                        "requires a single character string input",
+                        tag,
+                    ));
+                };
+                vec_s[0]
             }
-            _ => ',',
-        };
-
-        let mut result = from_delimited_data(headerless, sep, "CSV", input, name)?;
-        while let Some(item) = result.next().await {
-            yield item;
         }
-
+        _ => ',',
     };
 
-    Ok(stream.to_output_stream())
+    from_delimited_data(headerless, sep, "CSV", input, name).await
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_delimited_data.rs

@@ -1,7 +1,7 @@
 use crate::prelude::*;
 use csv::{ErrorKind, ReaderBuilder};
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{TaggedDictBuilder, UntaggedValue, Value};
 
 fn from_delimited_string_to_value(
     s: String,
@@ -41,7 +41,7 @@ fn from_delimited_string_to_value(
     Ok(UntaggedValue::Table(rows).into_value(&tag))
 }
 
-pub fn from_delimited_data(
+pub async fn from_delimited_data(
     headerless: bool,
     sep: char,
     format_name: &'static str,
@@ -49,37 +49,32 @@ pub fn from_delimited_data(
     name: Tag,
 ) -> Result<OutputStream, ShellError> {
     let name_tag = name;
+    let concat_string = input.collect_string(name_tag.clone()).await?;
 
-    let stream = async_stream! {
-        let concat_string = input.collect_string(name_tag.clone()).await?;
+    match from_delimited_string_to_value(concat_string.item, headerless, sep, name_tag.clone()) {
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            x => Ok(OutputStream::one(x)),
+        },
+        Err(err) => {
+            let line_one = match pretty_csv_error(err) {
+                Some(pretty) => format!("Could not parse as {} ({})", format_name, pretty),
+                None => format!("Could not parse as {}", format_name),
+            };
+            let line_two = format!("input cannot be parsed as {}", format_name);
 
-        match from_delimited_string_to_value(concat_string.item, headerless, sep, name_tag.clone()) {
-            Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
-                    for l in list {
-                        yield ReturnSuccess::value(l);
-                    }
-                }
-                x => yield ReturnSuccess::value(x),
-            },
-            Err(err) => {
-                let line_one = match pretty_csv_error(err) {
-                    Some(pretty) => format!("Could not parse as {} ({})", format_name,pretty),
-                    None => format!("Could not parse as {}", format_name),
-                };
-                let line_two = format!("input cannot be parsed as {}", format_name);
-                yield Err(ShellError::labeled_error_with_secondary(
-                    line_one,
-                    line_two,
-                    name_tag.clone(),
-                    "value originates from here",
-                    concat_string.tag,
-                ))
-            } ,
+            Err(ShellError::labeled_error_with_secondary(
+                line_one,
+                line_two,
+                name_tag.clone(),
+                "value originates from here",
+                concat_string.tag,
+            ))
         }
-    };
-
-    Ok(stream.to_output_stream())
+    }
 }
 
 fn pretty_csv_error(err: csv::Error) -> Option<String> {

crates/nu-cli/src/commands/from_ini.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 use std::collections::HashMap;
 
 pub struct FromINI;
@@ -25,7 +25,7 @@ impl WholeStreamCommand for FromINI {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_ini(args, registry)
+        from_ini(args, registry).await
     }
 }
 
@@ -64,36 +64,32 @@ pub fn from_ini_string_to_value(
     Ok(convert_ini_top_to_nu_value(&v, tag))
 }
 
-fn from_ini(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_ini(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
-        let concat_string = input.collect_string(tag.clone()).await?;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
+    let concat_string = input.collect_string(tag.clone()).await?;
 
-        match from_ini_string_to_value(concat_string.item, tag.clone()) {
-            Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
-                    for l in list {
-                        yield ReturnSuccess::value(l);
-                    }
-                }
-                x => yield ReturnSuccess::value(x),
-            },
-            Err(_) => {
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "Could not parse as INI",
-                    "input cannot be parsed as INI",
-                    &tag,
-                    "value originates from here",
-                    concat_string.tag,
-                ))
-            }
-        }
-    };
-
-    Ok(stream.to_output_stream())
+    match from_ini_string_to_value(concat_string.item, tag.clone()) {
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            x => Ok(OutputStream::one(x)),
+        },
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
+            "Could not parse as INI",
+            "input cannot be parsed as INI",
+            &tag,
+            "value originates from here",
+            concat_string.tag,
+        )),
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_sqlite.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 use rusqlite::{types::ValueRef, Connection, Row, NO_PARAMS};
 use std::io::Write;
 use std::path::Path;
@@ -27,7 +27,7 @@ impl WholeStreamCommand for FromSQLite {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_sqlite(args, registry)
+        from_sqlite(args, registry).await
     }
 }
 
@@ -52,7 +52,7 @@ impl WholeStreamCommand for FromDB {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_sqlite(args, registry)
+        from_sqlite(args, registry).await
     }
 }
 
@@ -65,6 +65,7 @@ pub fn convert_sqlite_file_to_nu_value(
     let mut meta_out = Vec::new();
     let mut meta_stmt = conn.prepare("select name from sqlite_master where type='table'")?;
     let mut meta_rows = meta_stmt.query(NO_PARAMS)?;
+
     while let Some(meta_row) = meta_rows.next()? {
         let table_name: String = meta_row.get(0)?;
         let mut meta_dict = TaggedDictBuilder::new(tag.clone());
@@ -134,37 +135,37 @@ pub fn from_sqlite_bytes_to_value(
     }
 }
 
-fn from_sqlite(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_sqlite(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
 
-        let bytes = input.collect_binary(tag.clone()).await?;
-        match from_sqlite_bytes_to_value(bytes.item, tag.clone()) {
-            Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
-                    for l in list {
-                        yield ReturnSuccess::value(l);
-                    }
-                }
-                _ => yield ReturnSuccess::value(x),
-            }
-            Err(err) => {
-                println!("{:?}", err);
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "Could not parse as SQLite",
-                    "input cannot be parsed as SQLite",
-                    &tag,
-                    "value originates from here",
-                    bytes.tag,
-                ))
-            }
+    let bytes = input.collect_binary(tag.clone()).await?;
+
+    match from_sqlite_bytes_to_value(bytes.item, tag.clone()) {
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            _ => Ok(OutputStream::one(x)),
+        },
+        Err(err) => {
+            println!("{:?}", err);
+
+            Err(ShellError::labeled_error_with_secondary(
+                "Could not parse as SQLite",
+                "input cannot be parsed as SQLite",
+                &tag,
+                "value originates from here",
+                bytes.tag,
+            ))
         }
-    };
-
-    Ok(stream.to_output_stream())
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_tsv.rs

@@ -34,23 +34,19 @@ impl WholeStreamCommand for FromTSV {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_tsv(args, registry)
+        from_tsv(args, registry).await
     }
 }
 
-fn from_tsv(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_tsv(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
     let name = args.call_info.name_tag.clone();
-    let stream = async_stream! {
-        let (FromTSVArgs { headerless }, mut input) = args.process(&registry).await?;
-        let mut result = from_delimited_data(headerless, '\t', "TSV", input, name)?;
+    let (FromTSVArgs { headerless }, input) = args.process(&registry).await?;
 
-        while let Some(output) = result.next().await {
-            yield output;
-        }
-    };
-
-    Ok(stream.to_output_stream())
+    from_delimited_data(headerless, '\t', "TSV", input, name).await
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_url.rs

@@ -24,44 +24,41 @@ impl WholeStreamCommand for FromURL {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_url(args, registry)
+        from_url(args, registry).await
     }
 }
 
-fn from_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_url(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
 
-        let concat_string = input.collect_string(tag.clone()).await?;
+    let concat_string = input.collect_string(tag.clone()).await?;
 
-        let result = serde_urlencoded::from_str::<Vec<(String, String)>>(&concat_string.item);
+    let result = serde_urlencoded::from_str::<Vec<(String, String)>>(&concat_string.item);
 
-        match result {
-            Ok(result) => {
-                let mut row = TaggedDictBuilder::new(tag);
+    match result {
+        Ok(result) => {
+            let mut row = TaggedDictBuilder::new(tag);
 
-                for (k,v) in result {
-                    row.insert_untagged(k, UntaggedValue::string(v));
-                }
-
-                yield ReturnSuccess::value(row.into_value());
-            }
-            _ => {
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "String not compatible with url-encoding",
-                    "input not url-encoded",
-                    tag,
-                    "value originates from here",
-                    concat_string.tag,
-                ));
+            for (k, v) in result {
+                row.insert_untagged(k, UntaggedValue::string(v));
             }
+
+            Ok(OutputStream::one(ReturnSuccess::value(row.into_value())))
         }
-    };
-
-    Ok(stream.to_output_stream())
+        _ => Err(ShellError::labeled_error_with_secondary(
+            "String not compatible with url-encoding",
+            "input not url-encoded",
+            tag,
+            "value originates from here",
+            concat_string.tag,
+        )),
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/from_vcf.rs

@@ -28,35 +28,42 @@ impl WholeStreamCommand for FromVcf {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_vcf(args, registry)
+        from_vcf(args, registry).await
     }
 }
 
-fn from_vcf(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_vcf(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
 
-        let input_string = input.collect_string(tag.clone()).await?.item;
-        let input_bytes = input_string.as_bytes();
-        let buf_reader = BufReader::new(input_bytes);
-        let parser = ical::VcardParser::new(buf_reader);
+    let input_string = input.collect_string(tag.clone()).await?.item;
+    let input_bytes = input_string.as_bytes();
+    let buf_reader = BufReader::new(input_bytes);
+    let parser = ical::VcardParser::new(buf_reader);
 
-        for contact in parser {
-            match contact {
-                Ok(c) => yield ReturnSuccess::value(contact_to_value(c, tag.clone())),
-                Err(_) => yield Err(ShellError::labeled_error(
+    let mut values_vec_deque = VecDeque::new();
+
+    for contact in parser {
+        match contact {
+            Ok(c) => {
+                values_vec_deque.push_back(ReturnSuccess::value(contact_to_value(c, tag.clone())))
+            }
+            Err(_) => {
+                return Err(ShellError::labeled_error(
                     "Could not parse as .vcf",
                     "input cannot be parsed as .vcf",
-                    tag.clone()
-                )),
+                    tag.clone(),
+                ))
             }
         }
-    };
+    }
 
-    Ok(stream.to_output_stream())
+    Ok(futures::stream::iter(values_vec_deque).to_output_stream())
 }
 
 fn contact_to_value(contact: VcardContact, tag: Tag) -> Value {

crates/nu-cli/src/commands/from_yaml.rs

@@ -1,7 +1,7 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 
 pub struct FromYAML;
 
@@ -24,7 +24,7 @@ impl WholeStreamCommand for FromYAML {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_yaml(args, registry)
+        from_yaml(args, registry).await
     }
 }
 
@@ -49,7 +49,7 @@ impl WholeStreamCommand for FromYML {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_yaml(args, registry)
+        from_yaml(args, registry).await
     }
 }
 
@@ -120,37 +120,33 @@ pub fn from_yaml_string_to_value(s: String, tag: impl Into<Tag>) -> Result<Value
     Ok(convert_yaml_value_to_nu_value(&v, tag)?)
 }
 
-fn from_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_yaml(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let args = args.evaluate_once(&registry).await?;
-        let tag = args.name_tag();
-        let input = args.input;
+    let args = args.evaluate_once(&registry).await?;
+    let tag = args.name_tag();
+    let input = args.input;
 
-        let concat_string = input.collect_string(tag.clone()).await?;
+    let concat_string = input.collect_string(tag.clone()).await?;
 
-        match from_yaml_string_to_value(concat_string.item, tag.clone()) {
-            Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
-                    for l in list {
-                        yield ReturnSuccess::value(l);
-                    }
-                }
-                x => yield ReturnSuccess::value(x),
-            },
-            Err(_) => {
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "Could not parse as YAML",
-                    "input cannot be parsed as YAML",
-                    &tag,
-                    "value originates from here",
-                    &concat_string.tag,
-                ))
-            }
-        }
-    };
-
-    Ok(stream.to_output_stream())
+    match from_yaml_string_to_value(concat_string.item, tag.clone()) {
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            x => Ok(OutputStream::one(x)),
+        },
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
+            "Could not parse as YAML",
+            "input cannot be parsed as YAML",
+            &tag,
+            "value originates from here",
+            &concat_string.tag,
+        )),
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/last.rs

@@ -35,7 +35,7 @@ impl WholeStreamCommand for Last {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        last(args, registry)
+        last(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -58,28 +58,30 @@ impl WholeStreamCommand for Last {
     }
 }
 
-fn last(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn last(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let (LastArgs { rows }, mut input) = args.process(&registry).await?;
-        let v: Vec<_> = input.into_vec().await;
+    let (LastArgs { rows }, input) = args.process(&registry).await?;
+    let v: Vec<_> = input.into_vec().await;
 
-        let rows_desired = if let Some(quantity) = rows {
-            *quantity
-        } else {
-         1
-        };
-
-        let count = (rows_desired as usize);
-        if count < v.len() {
-            let k = v.len() - count;
-            for x in v[k..].iter() {
-                let y: Value = x.clone();
-                yield ReturnSuccess::value(y)
-            }
-        }
+    let rows_desired = if let Some(quantity) = rows {
+        *quantity
+    } else {
+        1
     };
-    Ok(stream.to_output_stream())
+
+    let mut values_vec_deque = VecDeque::new();
+
+    let count = rows_desired as usize;
+
+    if count < v.len() {
+        let k = v.len() - count;
+
+        for x in v[k..].iter() {
+            values_vec_deque.push_back(ReturnSuccess::value(x.clone()));
+        }
+    }
+
+    Ok(futures::stream::iter(values_vec_deque).to_output_stream())
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/pwd.rs

@@ -24,7 +24,7 @@ impl WholeStreamCommand for Pwd {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        pwd(args, registry)
+        pwd(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -36,20 +36,15 @@ impl WholeStreamCommand for Pwd {
     }
 }
 
-pub fn pwd(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+pub async fn pwd(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
+    let shell_manager = args.shell_manager.clone();
+    let args = args.evaluate_once(&registry).await?;
 
-    let stream = async_stream! {
-        let shell_manager = args.shell_manager.clone();
-        let args = args.evaluate_once(&registry).await?;
-        let mut out = shell_manager.pwd(args)?;
-
-        while let Some(l) = out.next().await {
-            yield l;
-        }
-    };
-
-    Ok(stream.to_output_stream())
+    shell_manager.pwd(args)
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/reduce_by.rs

@@ -37,42 +37,37 @@ impl WholeStreamCommand for ReduceBy {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        reduce_by(args, registry)
+        reduce_by(args, registry).await
     }
 }
 
-pub fn reduce_by(
+pub async fn reduce_by(
     args: CommandArgs,
     registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
     let name = args.call_info.name_tag.clone();
-    let stream = async_stream! {
-        let (ReduceByArgs { reduce_with }, mut input) = args.process(&registry).await?;
-        let values: Vec<Value> = input.collect().await;
+    let (ReduceByArgs { reduce_with }, mut input) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
 
-        if values.is_empty() {
-            yield Err(ShellError::labeled_error(
-                    "Expected table from pipeline",
-                    "requires a table input",
-                    name
-                ))
-        } else {
+    if values.is_empty() {
+        return Err(ShellError::labeled_error(
+            "Expected table from pipeline",
+            "requires a table input",
+            name,
+        ));
+    }
 
-            let reduce_with = if let Some(reducer) = reduce_with {
-                Some(reducer.item().clone())
-            } else {
-                None
-            };
-
-            match reduce(&values[0], reduce_with, name) {
-                Ok(reduced) => yield ReturnSuccess::value(reduced),
-                Err(err) => yield Err(err)
-            }
-        }
+    let reduce_with = if let Some(reducer) = reduce_with {
+        Some(reducer.item().clone())
+    } else {
+        None
     };
 
-    Ok(stream.to_output_stream())
+    match reduce(&values[0], reduce_with, name) {
+        Ok(reduced) => Ok(OutputStream::one(ReturnSuccess::value(reduced))),
+        Err(err) => Err(err),
+    }
 }
 
 #[cfg(test)]

crates/nu-cli/src/commands/skip.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 
 pub struct Skip;
@@ -31,7 +31,7 @@ impl WholeStreamCommand for Skip {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        skip(args, registry)
+        skip(args, registry).await
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -46,27 +46,16 @@ impl WholeStreamCommand for Skip {
     }
 }
 
-fn skip(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn skip(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let registry = registry.clone();
-    let stream = async_stream! {
-        let (SkipArgs { rows }, mut input) = args.process(&registry).await?;
-        let mut rows_desired = if let Some(quantity) = rows {
-            *quantity
-        } else {
-            1
-        };
-
-        while let Some(input) = input.next().await {
-            if rows_desired == 0 {
-                yield ReturnSuccess::value(input);
-            }
-            if rows_desired > 0{
-                rows_desired -= 1;
-            }
-        }
+    let (SkipArgs { rows }, input) = args.process(&registry).await?;
+    let rows_desired = if let Some(quantity) = rows {
+        *quantity
+    } else {
+        1
     };
 
-    Ok(stream.to_output_stream())
+    Ok(input.skip(rows_desired).to_output_stream())
 }
 
 #[cfg(test)]