diff --git a/Cargo.lock b/Cargo.lock
index a764336209..66ff1285a0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1021,6 +1021,7 @@ dependencies = [
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_arena 0.1.0",
  "ra_db 0.1.0",
+ "ra_hir_expand 0.1.0",
  "ra_prof 0.1.0",
  "ra_syntax 0.1.0",
 ]
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 3f1c36941d..1a790b2f30 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -343,7 +343,7 @@ pub struct Struct {
 
 impl Struct {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -405,7 +405,7 @@ impl Union {
     }
 
     pub fn module(self, db: &impl HirDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn ty(self, db: &impl HirDatabase) -> Ty {
@@ -431,7 +431,7 @@ pub struct Enum {
 
 impl Enum {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -697,7 +697,7 @@ impl FnData {
 
 impl Function {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -775,7 +775,7 @@ pub struct Const {
 
 impl Const {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -872,7 +872,7 @@ pub struct Static {
 
 impl Static {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
@@ -901,7 +901,7 @@ pub struct Trait {
 
 impl Trait {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -1003,7 +1003,7 @@ pub struct TypeAlias {
 
 impl TypeAlias {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index 8b33f25f7a..5c7f61eefb 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -1,9 +1,6 @@
 //! FIXME: write short doc here
 
-use ra_syntax::{
-    ast::{self, AstNode},
-    SyntaxNode,
-};
+use ra_syntax::ast::{self, AstNode};
 
 use crate::{
     db::{AstDatabase, DefDatabase, HirDatabase},
@@ -12,26 +9,13 @@ use crate::{
     ModuleSource, Static, Struct, StructField, Trait, TypeAlias, Union,
 };
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub struct Source<T> {
-    pub file_id: HirFileId,
-    pub ast: T,
-}
+pub use hir_def::Source;
 
 pub trait HasSource {
     type Ast;
     fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<Self::Ast>;
 }
 
-impl<T> Source<T> {
-    pub(crate) fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
-        Source { file_id: self.file_id, ast: f(self.ast) }
-    }
-    pub(crate) fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
-        db.parse_or_expand(self.file_id).expect("source created from invalid file")
-    }
-}
-
 /// NB: Module is !HasSource, because it has two source nodes at the same time:
 /// definition and declaration.
 impl Module {
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index da8ae6ef47..8f6cb2da7d 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -2,8 +2,8 @@
 
 use std::sync::Arc;
 
-use ra_db::{salsa, SourceDatabase};
-use ra_syntax::{ast, SmolStr};
+use ra_db::salsa;
+use ra_syntax::SmolStr;
 
 use crate::{
     adt::{EnumData, StructData},
@@ -23,34 +23,12 @@ use crate::{
     Static, Struct, StructField, Trait, TypeAlias,
 };
 
+pub use hir_def::db::{InternDatabase, InternDatabaseStorage};
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
     ParseMacroQuery,
 };
 
-/// We store all interned things in the single QueryGroup.
-///
-/// This is done mainly to allow both "volatile" `AstDatabase` and "stable"
-/// `DefDatabase` to access macros, without adding hard dependencies between the
-/// two.
-#[salsa::query_group(InternDatabaseStorage)]
-pub trait InternDatabase: SourceDatabase {
-    #[salsa::interned]
-    fn intern_function(&self, loc: ids::ItemLoc<ast::FnDef>) -> ids::FunctionId;
-    #[salsa::interned]
-    fn intern_struct(&self, loc: ids::ItemLoc<ast::StructDef>) -> ids::StructId;
-    #[salsa::interned]
-    fn intern_enum(&self, loc: ids::ItemLoc<ast::EnumDef>) -> ids::EnumId;
-    #[salsa::interned]
-    fn intern_const(&self, loc: ids::ItemLoc<ast::ConstDef>) -> ids::ConstId;
-    #[salsa::interned]
-    fn intern_static(&self, loc: ids::ItemLoc<ast::StaticDef>) -> ids::StaticId;
-    #[salsa::interned]
-    fn intern_trait(&self, loc: ids::ItemLoc<ast::TraitDef>) -> ids::TraitId;
-    #[salsa::interned]
-    fn intern_type_alias(&self, loc: ids::ItemLoc<ast::TypeAliasDef>) -> ids::TypeAliasId;
-}
-
 // This database uses `AstDatabase` internally,
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index 291f2a14ac..93713bb142 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -208,6 +208,6 @@ where
     let module_src =
         crate::ModuleSource::from_child_node(db, src.file_id.original_file(db), &src.ast.syntax());
     let module = Module::from_definition(db, Source { file_id: src.file_id, ast: module_src })?;
-    let ctx = LocationCtx::new(db, module, src.file_id);
+    let ctx = LocationCtx::new(db, module.id, src.file_id);
     Some(DEF::from_ast(ctx, &src.ast))
 }
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index dea288eb7b..fe083c0c65 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -5,16 +5,12 @@
 //! This module defines a bunch of ids we are using. The most important ones are
 //! probably `HirFileId` and `DefId`.
 
-use std::hash::{Hash, Hasher};
-
 use ra_db::salsa;
-use ra_syntax::{ast, AstNode};
 
-use crate::{
-    db::{AstDatabase, InternDatabase},
-    AstId, FileAstId, Module, Source,
+pub use hir_def::{
+    AstItemDef, ConstId, EnumId, FunctionId, ItemLoc, LocationCtx, StaticId, StructId, TraitId,
+    TypeAliasId,
 };
-
 pub use hir_expand::{HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFile, MacroFileKind};
 
 macro_rules! impl_intern_key {
@@ -30,163 +26,6 @@ macro_rules! impl_intern_key {
     };
 }
 
-#[derive(Debug)]
-pub struct ItemLoc<N: AstNode> {
-    pub(crate) module: Module,
-    ast_id: AstId<N>,
-}
-
-impl<N: AstNode> PartialEq for ItemLoc<N> {
-    fn eq(&self, other: &Self) -> bool {
-        self.module == other.module && self.ast_id == other.ast_id
-    }
-}
-impl<N: AstNode> Eq for ItemLoc<N> {}
-impl<N: AstNode> Hash for ItemLoc<N> {
-    fn hash<H: Hasher>(&self, hasher: &mut H) {
-        self.module.hash(hasher);
-        self.ast_id.hash(hasher);
-    }
-}
-
-impl<N: AstNode> Clone for ItemLoc<N> {
-    fn clone(&self) -> ItemLoc<N> {
-        ItemLoc { module: self.module, ast_id: self.ast_id }
-    }
-}
-
-#[derive(Clone, Copy)]
-pub(crate) struct LocationCtx<DB> {
-    db: DB,
-    module: Module,
-    file_id: HirFileId,
-}
-
-impl<'a, DB> LocationCtx<&'a DB> {
-    pub(crate) fn new(db: &'a DB, module: Module, file_id: HirFileId) -> LocationCtx<&'a DB> {
-        LocationCtx { db, module, file_id }
-    }
-}
-
-impl<'a, DB: AstDatabase + InternDatabase> LocationCtx<&'a DB> {
-    pub(crate) fn to_def<N, DEF>(self, ast: &N) -> DEF
-    where
-        N: AstNode,
-        DEF: AstItemDef<N>,
-    {
-        DEF::from_ast(self, ast)
-    }
-}
-
-pub(crate) trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<N>) -> Self;
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<N>;
-
-    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + InternDatabase)>, ast: &N) -> Self {
-        let items = ctx.db.ast_id_map(ctx.file_id);
-        let item_id = items.ast_id(ast);
-        Self::from_ast_id(ctx, item_id)
-    }
-    fn from_ast_id(ctx: LocationCtx<&impl InternDatabase>, ast_id: FileAstId<N>) -> Self {
-        let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
-        Self::intern(ctx.db, loc)
-    }
-    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
-        let loc = self.lookup_intern(db);
-        let ast = loc.ast_id.to_node(db);
-        Source { file_id: loc.ast_id.file_id(), ast }
-    }
-    fn module(self, db: &impl InternDatabase) -> Module {
-        let loc = self.lookup_intern(db);
-        loc.module
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct FunctionId(salsa::InternId);
-impl_intern_key!(FunctionId);
-
-impl AstItemDef<ast::FnDef> for FunctionId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
-        db.intern_function(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
-        db.lookup_intern_function(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StructId(salsa::InternId);
-impl_intern_key!(StructId);
-impl AstItemDef<ast::StructDef> for StructId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
-        db.intern_struct(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
-        db.lookup_intern_struct(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct EnumId(salsa::InternId);
-impl_intern_key!(EnumId);
-impl AstItemDef<ast::EnumDef> for EnumId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
-        db.intern_enum(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::EnumDef> {
-        db.lookup_intern_enum(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct ConstId(salsa::InternId);
-impl_intern_key!(ConstId);
-impl AstItemDef<ast::ConstDef> for ConstId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
-        db.intern_const(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::ConstDef> {
-        db.lookup_intern_const(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StaticId(salsa::InternId);
-impl_intern_key!(StaticId);
-impl AstItemDef<ast::StaticDef> for StaticId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
-        db.intern_static(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StaticDef> {
-        db.lookup_intern_static(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TraitId(salsa::InternId);
-impl_intern_key!(TraitId);
-impl AstItemDef<ast::TraitDef> for TraitId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
-        db.intern_trait(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TraitDef> {
-        db.lookup_intern_trait(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TypeAliasId(salsa::InternId);
-impl_intern_key!(TypeAliasId);
-impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
-        db.intern_type_alias(loc)
-    }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TypeAliasDef> {
-        db.lookup_intern_type_alias(self)
-    }
-}
-
 /// This exists just for Chalk, because Chalk just has a single `StructId` where
 /// we have different kinds of ADTs, primitive types and special type
 /// constructors like tuples and function pointers.
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index fde47c264a..06f21fc33e 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -129,7 +129,7 @@ impl ImplData {
     ) -> Self {
         let target_trait = node.target_trait().map(TypeRef::from_ast);
         let target_type = TypeRef::from_ast_opt(node.target_type());
-        let ctx = LocationCtx::new(db, module, file_id);
+        let ctx = LocationCtx::new(db, module.id, file_id);
         let negative = node.is_negative();
         let items = if let Some(item_list) = node.item_list() {
             item_list
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index dd5f9d4ba1..a94a0554c8 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -641,7 +641,7 @@ where
 
     fn define_def(&mut self, def: &raw::DefData) {
         let module = Module::new(self.def_collector.def_map.krate, self.module_id);
-        let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id);
+        let ctx = LocationCtx::new(self.def_collector.db, module.id, self.file_id);
 
         macro_rules! def {
             ($kind:ident, $ast_id:ident) => {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index a907d6a9f9..730c332264 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -64,7 +64,7 @@ fn def_with_body_from_child_node(
 ) -> Option<DefWithBody> {
     let src = crate::ModuleSource::from_child_node(db, file_id, node);
     let module = Module::from_definition(db, crate::Source { file_id: file_id.into(), ast: src })?;
-    let ctx = LocationCtx::new(db, module, file_id.into());
+    let ctx = LocationCtx::new(db, module.id, file_id.into());
 
     node.ancestors().find_map(|node| {
         if let Some(def) = ast::FnDef::cast(node.clone()) {
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
index e39511518d..22f1880493 100644
--- a/crates/ra_hir/src/traits.rs
+++ b/crates/ra_hir/src/traits.rs
@@ -27,7 +27,7 @@ impl TraitData {
         let src = tr.source(db);
         let name = src.ast.name().map(|n| n.as_name());
         let module = tr.module(db);
-        let ctx = LocationCtx::new(db, module, src.file_id);
+        let ctx = LocationCtx::new(db, module.id, src.file_id);
         let auto = src.ast.is_auto();
         let items = if let Some(item_list) = src.ast.item_list() {
             item_list
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index aec484feb2..ab66515bee 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -162,11 +162,11 @@ impl ToChalk for Trait {
     type Chalk = chalk_ir::TraitId;
 
     fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TraitId {
-        self.id.into()
+        chalk_ir::TraitId(id_to_chalk(self.id))
     }
 
     fn from_chalk(_db: &impl HirDatabase, trait_id: chalk_ir::TraitId) -> Trait {
-        Trait { id: trait_id.into() }
+        Trait { id: id_from_chalk(trait_id.0) }
     }
 }
 
@@ -198,11 +198,11 @@ impl ToChalk for TypeAlias {
     type Chalk = chalk_ir::TypeId;
 
     fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TypeId {
-        self.id.into()
+        chalk_ir::TypeId(id_to_chalk(self.id))
     }
 
-    fn from_chalk(_db: &impl HirDatabase, impl_id: chalk_ir::TypeId) -> TypeAlias {
-        TypeAlias { id: impl_id.into() }
+    fn from_chalk(_db: &impl HirDatabase, type_alias_id: chalk_ir::TypeId) -> TypeAlias {
+        TypeAlias { id: id_from_chalk(type_alias_id.0) }
     }
 }
 
@@ -775,30 +775,6 @@ fn id_to_chalk<T: InternKey>(salsa_id: T) -> chalk_ir::RawId {
     chalk_ir::RawId { index: salsa_id.as_intern_id().as_u32() }
 }
 
-impl From<chalk_ir::TraitId> for crate::ids::TraitId {
-    fn from(trait_id: chalk_ir::TraitId) -> Self {
-        id_from_chalk(trait_id.0)
-    }
-}
-
-impl From<crate::ids::TraitId> for chalk_ir::TraitId {
-    fn from(trait_id: crate::ids::TraitId) -> Self {
-        chalk_ir::TraitId(id_to_chalk(trait_id))
-    }
-}
-
-impl From<chalk_ir::TypeId> for crate::ids::TypeAliasId {
-    fn from(type_id: chalk_ir::TypeId) -> Self {
-        id_from_chalk(type_id.0)
-    }
-}
-
-impl From<crate::ids::TypeAliasId> for chalk_ir::TypeId {
-    fn from(type_id: crate::ids::TypeAliasId) -> Self {
-        chalk_ir::TypeId(id_to_chalk(type_id))
-    }
-}
-
 impl From<chalk_ir::StructId> for crate::ids::TypeCtorId {
     fn from(struct_id: chalk_ir::StructId) -> Self {
         id_from_chalk(struct_id.0)
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index f22a678eb7..75e93f2547 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -11,3 +11,4 @@ ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
 ra_syntax = { path = "../ra_syntax" }
 ra_prof = { path = "../ra_prof" }
+hir_expand = { path = "../ra_hir_expand", package = "ra_hir_expand" }
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
new file mode 100644
index 0000000000..f6f976c860
--- /dev/null
+++ b/crates/ra_hir_def/src/db.rs
@@ -0,0 +1,22 @@
+//! Defines database & queries for name resolution.
+
+use ra_db::{salsa, SourceDatabase};
+use ra_syntax::ast;
+
+#[salsa::query_group(InternDatabaseStorage)]
+pub trait InternDatabase: SourceDatabase {
+    #[salsa::interned]
+    fn intern_function(&self, loc: crate::ItemLoc<ast::FnDef>) -> crate::FunctionId;
+    #[salsa::interned]
+    fn intern_struct(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::StructId;
+    #[salsa::interned]
+    fn intern_enum(&self, loc: crate::ItemLoc<ast::EnumDef>) -> crate::EnumId;
+    #[salsa::interned]
+    fn intern_const(&self, loc: crate::ItemLoc<ast::ConstDef>) -> crate::ConstId;
+    #[salsa::interned]
+    fn intern_static(&self, loc: crate::ItemLoc<ast::StaticDef>) -> crate::StaticId;
+    #[salsa::interned]
+    fn intern_trait(&self, loc: crate::ItemLoc<ast::TraitDef>) -> crate::TraitId;
+    #[salsa::interned]
+    fn intern_type_alias(&self, loc: crate::ItemLoc<ast::TypeAliasDef>) -> crate::TypeAliasId;
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index f5dd2ae6fb..4d6b9db033 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -1,5 +1,37 @@
+//! `hir_def` crate contains everything between macro expansion and type
+//! inference.
+//!
+//! It defines various items (structs, enums, traits) which comprises Rust code,
+//! as well as an algorithm for resolving paths to such entities.
+//!
+//! Note that `hir_def` is a work in progress, so not all of the above is
+//! actually true.
+
+pub mod db;
+
+use std::hash::{Hash, Hasher};
+
+use hir_expand::{ast_id_map::FileAstId, db::AstDatabase, AstId, HirFileId};
 use ra_arena::{impl_arena_id, RawId};
-use ra_db::CrateId;
+use ra_db::{salsa, CrateId};
+use ra_syntax::{ast, AstNode, SyntaxNode};
+
+use crate::db::InternDatabase;
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct Source<T> {
+    pub file_id: HirFileId,
+    pub ast: T,
+}
+
+impl<T> Source<T> {
+    pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
+        Source { file_id: self.file_id, ast: f(self.ast) }
+    }
+    pub fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
+        db.parse_or_expand(self.file_id).expect("source created from invalid file")
+    }
+}
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ModuleId {
@@ -12,3 +44,173 @@ pub struct ModuleId {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct CrateModuleId(RawId);
 impl_arena_id!(CrateModuleId);
+
+macro_rules! impl_intern_key {
+    ($name:ident) => {
+        impl salsa::InternKey for $name {
+            fn from_intern_id(v: salsa::InternId) -> Self {
+                $name(v)
+            }
+            fn as_intern_id(&self) -> salsa::InternId {
+                self.0
+            }
+        }
+    };
+}
+
+#[derive(Debug)]
+pub struct ItemLoc<N: AstNode> {
+    pub(crate) module: ModuleId,
+    ast_id: AstId<N>,
+}
+
+impl<N: AstNode> PartialEq for ItemLoc<N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.module == other.module && self.ast_id == other.ast_id
+    }
+}
+impl<N: AstNode> Eq for ItemLoc<N> {}
+impl<N: AstNode> Hash for ItemLoc<N> {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.module.hash(hasher);
+        self.ast_id.hash(hasher);
+    }
+}
+
+impl<N: AstNode> Clone for ItemLoc<N> {
+    fn clone(&self) -> ItemLoc<N> {
+        ItemLoc { module: self.module, ast_id: self.ast_id }
+    }
+}
+
+#[derive(Clone, Copy)]
+pub struct LocationCtx<DB> {
+    db: DB,
+    module: ModuleId,
+    file_id: HirFileId,
+}
+
+impl<'a, DB> LocationCtx<&'a DB> {
+    pub fn new(db: &'a DB, module: ModuleId, file_id: HirFileId) -> LocationCtx<&'a DB> {
+        LocationCtx { db, module, file_id }
+    }
+}
+
+impl<'a, DB: AstDatabase + InternDatabase> LocationCtx<&'a DB> {
+    pub fn to_def<N, DEF>(self, ast: &N) -> DEF
+    where
+        N: AstNode,
+        DEF: AstItemDef<N>,
+    {
+        DEF::from_ast(self, ast)
+    }
+}
+
+pub trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<N>) -> Self;
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<N>;
+
+    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + InternDatabase)>, ast: &N) -> Self {
+        let items = ctx.db.ast_id_map(ctx.file_id);
+        let item_id = items.ast_id(ast);
+        Self::from_ast_id(ctx, item_id)
+    }
+    fn from_ast_id(ctx: LocationCtx<&impl InternDatabase>, ast_id: FileAstId<N>) -> Self {
+        let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
+        Self::intern(ctx.db, loc)
+    }
+    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
+        let loc = self.lookup_intern(db);
+        let ast = loc.ast_id.to_node(db);
+        Source { file_id: loc.ast_id.file_id(), ast }
+    }
+    fn module(self, db: &impl InternDatabase) -> ModuleId {
+        let loc = self.lookup_intern(db);
+        loc.module
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FunctionId(salsa::InternId);
+impl_intern_key!(FunctionId);
+
+impl AstItemDef<ast::FnDef> for FunctionId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
+        db.intern_function(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
+        db.lookup_intern_function(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StructId(salsa::InternId);
+impl_intern_key!(StructId);
+impl AstItemDef<ast::StructDef> for StructId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
+        db.intern_struct(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
+        db.lookup_intern_struct(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumId(salsa::InternId);
+impl_intern_key!(EnumId);
+impl AstItemDef<ast::EnumDef> for EnumId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
+        db.intern_enum(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::EnumDef> {
+        db.lookup_intern_enum(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ConstId(salsa::InternId);
+impl_intern_key!(ConstId);
+impl AstItemDef<ast::ConstDef> for ConstId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
+        db.intern_const(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::ConstDef> {
+        db.lookup_intern_const(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StaticId(salsa::InternId);
+impl_intern_key!(StaticId);
+impl AstItemDef<ast::StaticDef> for StaticId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
+        db.intern_static(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StaticDef> {
+        db.lookup_intern_static(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TraitId(salsa::InternId);
+impl_intern_key!(TraitId);
+impl AstItemDef<ast::TraitDef> for TraitId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
+        db.intern_trait(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TraitDef> {
+        db.lookup_intern_trait(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeAliasId(salsa::InternId);
+impl_intern_key!(TypeAliasId);
+impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
+        db.intern_type_alias(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TypeAliasDef> {
+        db.lookup_intern_type_alias(self)
+    }
+}
diff --git a/crates/ra_ide_api/src/completion/complete_path.rs b/crates/ra_ide_api/src/completion/complete_path.rs
index 23dece73c2..956d8ce49c 100644
--- a/crates/ra_ide_api/src/completion/complete_path.rs
+++ b/crates/ra_ide_api/src/completion/complete_path.rs
@@ -50,7 +50,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                 hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
                 _ => unreachable!(),
             };
-            let krate = ctx.module.and_then(|m| m.krate(ctx.db));
+            let krate = ctx.module.map(|m| m.krate());
             if let Some(krate) = krate {
                 ty.iterate_impl_items(ctx.db, krate, |item| {
                     match item {
diff --git a/crates/ra_ide_api/src/impls.rs b/crates/ra_ide_api/src/impls.rs
index 7fc1b1efa8..b899ed3a5f 100644
--- a/crates/ra_ide_api/src/impls.rs
+++ b/crates/ra_ide_api/src/impls.rs
@@ -51,7 +51,7 @@ fn impls_for_def(
         }
     };
 
-    let krate = module.krate(db)?;
+    let krate = module.krate();
     let impls = db.impls_in_crate(krate);
 
     Some(
@@ -72,7 +72,7 @@ fn impls_for_trait(
     let src = hir::Source { file_id: position.file_id.into(), ast: node.clone() };
     let tr = hir::Trait::from_source(db, src)?;
 
-    let krate = module.krate(db)?;
+    let krate = module.krate();
     let impls = db.impls_in_crate(krate);
 
     Some(
diff --git a/crates/ra_ide_api/src/parent_module.rs b/crates/ra_ide_api/src/parent_module.rs
index 5665098499..4c57566e2a 100644
--- a/crates/ra_ide_api/src/parent_module.rs
+++ b/crates/ra_ide_api/src/parent_module.rs
@@ -27,10 +27,7 @@ pub(crate) fn crate_for(db: &RootDatabase, file_id: FileId) -> Vec<CrateId> {
             Some(it) => it,
             None => return Vec::new(),
         };
-    let krate = match module.krate(db) {
-        Some(it) => it,
-        None => return Vec::new(),
-    };
+    let krate = module.krate();
     vec![krate.crate_id()]
 }
 
diff --git a/crates/ra_ide_api/src/references/search_scope.rs b/crates/ra_ide_api/src/references/search_scope.rs
index b6eb248b74..dbd1af5976 100644
--- a/crates/ra_ide_api/src/references/search_scope.rs
+++ b/crates/ra_ide_api/src/references/search_scope.rs
@@ -120,7 +120,7 @@ impl NameDefinition {
                 return SearchScope::new(res);
             }
             if vis.as_str() == "pub" {
-                let krate = self.container.krate(db).unwrap();
+                let krate = self.container.krate();
                 let crate_graph = db.crate_graph();
                 for crate_id in crate_graph.iter() {
                     let mut crate_deps = crate_graph.dependencies(crate_id);