Merge pull request #118 from Nadrieril/clarify-types

Clarify naming and file organization

14 files changed, 300 insertions, 377 deletions

diff --git a/dhall/src/syntax/core/expr.rs b/dhall/src/syntax/ast/expr.rs
index 5b9f401..48c48d8 100644
--- a/dhall/src/syntax/core/expr.rs
+++ b/dhall/src/syntax/ast/expr.rs
@@ -1,51 +1,15 @@
 use crate::syntax::map::{DupTreeMap, DupTreeSet};
-use crate::syntax::visitor::{self, ExprFMutVisitor, ExprFVisitor};
+use crate::syntax::visitor::{self, ExprKindMutVisitor, ExprKindVisitor};
 use crate::syntax::*;
 
 pub type Integer = isize;
 pub type Natural = usize;
 pub type Double = NaiveDouble;
 
-pub fn trivial_result<T>(x: Result<T, !>) -> T {
-    match x {
-        Ok(x) => x,
-        Err(e) => e,
-    }
-}
-
 /// Double with bitwise equality
 #[derive(Debug, Copy, Clone)]
 pub struct NaiveDouble(f64);
 
-impl PartialEq for NaiveDouble {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.to_bits() == other.0.to_bits()
-    }
-}
-
-impl Eq for NaiveDouble {}
-
-impl std::hash::Hash for NaiveDouble {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: std::hash::Hasher,
-    {
-        self.0.to_bits().hash(state)
-    }
-}
-
-impl From<f64> for NaiveDouble {
-    fn from(x: f64) -> Self {
-        NaiveDouble(x)
-    }
-}
-
-impl From<NaiveDouble> for f64 {
-    fn from(x: NaiveDouble) -> f64 {
-        x.0
-    }
-}
-
 /// Constants for a pure type system
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Const {
@@ -62,18 +26,6 @@ pub enum Const {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct V<Label>(pub Label, pub usize);
 
-// This is only for the specific `Label` type, not generic
-impl From<Label> for V<Label> {
-    fn from(x: Label) -> V<Label> {
-        V(x, 0)
-    }
-}
-impl<'a> From<&'a Label> for V<Label> {
-    fn from(x: &'a Label) -> V<Label> {
-        V(x.clone(), 0)
-    }
-}
-
 // Definition order must match precedence order for
 // pretty-printing to work correctly
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -142,33 +94,19 @@ pub enum Builtin {
 
 // Each node carries an annotation.
 #[derive(Debug, Clone)]
-pub struct Expr<Embed>(Box<(RawExpr<Embed>, Span)>);
-
-pub type RawExpr<Embed> = ExprF<Expr<Embed>, Embed>;
-
-impl<Embed: PartialEq> std::cmp::PartialEq for Expr<Embed> {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.as_ref().0 == other.0.as_ref().0
-    }
+pub struct Expr<Embed> {
+    kind: Box<ExprKind<Expr<Embed>, Embed>>,
+    span: Span,
 }
 
-impl<Embed: Eq> std::cmp::Eq for Expr<Embed> {}
-
-impl<Embed: std::hash::Hash> std::hash::Hash for Expr<Embed> {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: std::hash::Hasher,
-    {
-        (self.0).0.hash(state)
-    }
-}
+pub type UnspannedExpr<Embed> = ExprKind<Expr<Embed>, Embed>;
 
 /// Syntax tree for expressions
 // Having the recursion out of the enum definition enables writing
 // much more generic code and improves pattern-matching behind
 // smart pointers.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum ExprF<SubExpr, Embed> {
+pub enum ExprKind<SubExpr, Embed> {
     Const(Const),
     ///  `x`
     ///  `x@n`
@@ -231,12 +169,12 @@ pub enum ExprF<SubExpr, Embed> {
     Embed(Embed),
 }
 
-impl<SE, E> ExprF<SE, E> {
+impl<SE, E> ExprKind<SE, E> {
     pub fn traverse_ref_with_special_handling_of_binders<'a, SE2, Err>(
         &'a self,
         visit_subexpr: impl FnMut(&'a SE) -> Result<SE2, Err>,
         visit_under_binder: impl FnOnce(&'a Label, &'a SE) -> Result<SE2, Err>,
-    ) -> Result<ExprF<SE2, E>, Err>
+    ) -> Result<ExprKind<SE2, E>, Err>
     where
         E: Clone,
     {
@@ -250,7 +188,7 @@ impl<SE, E> ExprF<SE, E> {
     fn traverse_ref<'a, SE2, Err>(
         &'a self,
         visit_subexpr: impl FnMut(&'a SE) -> Result<SE2, Err>,
-    ) -> Result<ExprF<SE2, E>, Err>
+    ) -> Result<ExprKind<SE2, E>, Err>
     where
         E: Clone,
     {
@@ -268,7 +206,7 @@ impl<SE, E> ExprF<SE, E> {
         &'a self,
         mut map_subexpr: impl FnMut(&'a SE) -> SE2,
         mut map_under_binder: impl FnMut(&'a Label, &'a SE) -> SE2,
-    ) -> ExprF<SE2, E>
+    ) -> ExprKind<SE2, E>
     where
         E: Clone,
     {
@@ -281,7 +219,7 @@ impl<SE, E> ExprF<SE, E> {
     pub fn map_ref<'a, SE2>(
         &'a self,
         mut map_subexpr: impl FnMut(&'a SE) -> SE2,
-    ) -> ExprF<SE2, E>
+    ) -> ExprKind<SE2, E>
     where
         E: Clone,
     {
@@ -294,22 +232,25 @@ impl<SE, E> ExprF<SE, E> {
 }
 
 impl<E> Expr<E> {
-    pub fn as_ref(&self) -> &RawExpr<E> {
-        &self.0.as_ref().0
-    }
-    pub fn as_mut(&mut self) -> &mut RawExpr<E> {
-        &mut self.0.as_mut().0
+    pub fn as_ref(&self) -> &UnspannedExpr<E> {
+        &self.kind
     }
     pub fn span(&self) -> Span {
-        self.0.as_ref().1.clone()
+        self.span.clone()
     }
 
-    pub fn new(x: RawExpr<E>, n: Span) -> Self {
-        Expr(Box::new((x, n)))
+    pub fn new(kind: UnspannedExpr<E>, span: Span) -> Self {
+        Expr {
+            kind: Box::new(kind),
+            span,
+        }
     }
 
-    pub fn rewrap<E2>(&self, x: RawExpr<E2>) -> Expr<E2> {
-        Expr(Box::new((x, (self.0).1.clone())))
+    pub fn rewrap<E2>(&self, kind: UnspannedExpr<E2>) -> Expr<E2> {
+        Expr {
+            kind: Box::new(kind),
+            span: self.span.clone(),
+        }
     }
 
     pub fn traverse_resolve_mut<Err, F1>(
@@ -320,21 +261,21 @@ impl<E> Expr<E> {
         E: Clone,
         F1: FnMut(Import<Expr<E>>) -> Result<E, Err>,
     {
-        match self.as_mut() {
-            ExprF::BinOp(BinOp::ImportAlt, l, r) => {
-                let garbage_expr = ExprF::BoolLit(false);
+        match self.kind.as_mut() {
+            ExprKind::BinOp(BinOp::ImportAlt, l, r) => {
+                let garbage_expr = ExprKind::BoolLit(false);
                 let new_self = if l.traverse_resolve_mut(f).is_ok() {
                     l
                 } else {
                     r.traverse_resolve_mut(f)?;
                     r
                 };
-                *self.as_mut() =
-                    std::mem::replace(new_self.as_mut(), garbage_expr);
+                *self.kind =
+                    std::mem::replace(new_self.kind.as_mut(), garbage_expr);
             }
             _ => {
-                self.as_mut().traverse_mut(|e| e.traverse_resolve_mut(f))?;
-                if let ExprF::Import(import) = self.as_mut() {
+                self.kind.traverse_mut(|e| e.traverse_resolve_mut(f))?;
+                if let ExprKind::Import(import) = self.kind.as_mut() {
                     let garbage_import = Import {
                         mode: ImportMode::Code,
                         location: ImportLocation::Missing,
@@ -342,7 +283,7 @@ impl<E> Expr<E> {
                     };
                     // Move out of &mut import
                     let import = std::mem::replace(import, garbage_import);
-                    *self.as_mut() = ExprF::Embed(f(import)?);
+                    *self.kind = ExprKind::Embed(f(import)?);
                 }
             }
         }
@@ -350,16 +291,6 @@ impl<E> Expr<E> {
     }
 }
 
-/// Add an isize to an usize
-/// Returns `None` on over/underflow
-fn add_ui(u: usize, i: isize) -> Option<usize> {
-    Some(if i < 0 {
-        u.checked_sub(i.checked_neg()? as usize)?
-    } else {
-        u.checked_add(i as usize)?
-    })
-}
-
 impl<Label: PartialEq + Clone> V<Label> {
     pub fn shift(&self, delta: isize, var: &V<Label>) -> Option<Self> {
         let V(x, n) = var;
@@ -375,3 +306,73 @@ impl<Label: PartialEq + Clone> V<Label> {
         self.shift(-1, &V(x.clone(), 0))
     }
 }
+
+pub fn trivial_result<T>(x: Result<T, !>) -> T {
+    match x {
+        Ok(x) => x,
+        Err(e) => e,
+    }
+}
+
+/// Add an isize to an usize
+/// Returns `None` on over/underflow
+fn add_ui(u: usize, i: isize) -> Option<usize> {
+    Some(if i < 0 {
+        u.checked_sub(i.checked_neg()? as usize)?
+    } else {
+        u.checked_add(i as usize)?
+    })
+}
+
+impl PartialEq for NaiveDouble {
+    fn eq(&self, other: &Self) -> bool {
+        self.0.to_bits() == other.0.to_bits()
+    }
+}
+
+impl Eq for NaiveDouble {}
+
+impl std::hash::Hash for NaiveDouble {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: std::hash::Hasher,
+    {
+        self.0.to_bits().hash(state)
+    }
+}
+
+impl From<f64> for NaiveDouble {
+    fn from(x: f64) -> Self {
+        NaiveDouble(x)
+    }
+}
+
+impl From<NaiveDouble> for f64 {
+    fn from(x: NaiveDouble) -> f64 {
+        x.0
+    }
+}
+
+/// This is only for the specific `Label` type, not generic
+impl From<Label> for V<Label> {
+    fn from(x: Label) -> V<Label> {
+        V(x, 0)
+    }
+}
+
+impl<Embed: PartialEq> std::cmp::PartialEq for Expr<Embed> {
+    fn eq(&self, other: &Self) -> bool {
+        self.kind == other.kind
+    }
+}
+
+impl<Embed: Eq> std::cmp::Eq for Expr<Embed> {}
+
+impl<Embed: std::hash::Hash> std::hash::Hash for Expr<Embed> {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: std::hash::Hasher,
+    {
+        self.kind.hash(state)
+    }
+}
diff --git a/dhall/src/syntax/core/import.rs b/dhall/src/syntax/ast/import.rs
index da3e99b..da3e99b 100644
--- a/dhall/src/syntax/core/import.rs
+++ b/dhall/src/syntax/ast/import.rs
diff --git a/dhall/src/syntax/core/label.rs b/dhall/src/syntax/ast/label.rs
index 43c3f53..43c3f53 100644
--- a/dhall/src/syntax/core/label.rs
+++ b/dhall/src/syntax/ast/label.rs
diff --git a/dhall/src/syntax/core/map.rs b/dhall/src/syntax/ast/map.rs
index c4c6126..c4c6126 100644
--- a/dhall/src/syntax/core/map.rs
+++ b/dhall/src/syntax/ast/map.rs
diff --git a/dhall/src/syntax/core/mod.rs b/dhall/src/syntax/ast/mod.rs
index 66bf229..1950154 100644
--- a/dhall/src/syntax/core/mod.rs
+++ b/dhall/src/syntax/ast/mod.rs
@@ -8,6 +8,5 @@ mod span;
 pub use span::*;
 mod text;
 pub use text::*;
-pub mod context;
 pub mod map;
 pub mod visitor;
diff --git a/dhall/src/syntax/core/span.rs b/dhall/src/syntax/ast/span.rs
index f9c7008..f9c7008 100644
--- a/dhall/src/syntax/core/span.rs
+++ b/dhall/src/syntax/ast/span.rs
diff --git a/dhall/src/syntax/core/text.rs b/dhall/src/syntax/ast/text.rs
index fb390ee..fb390ee 100644
--- a/dhall/src/syntax/core/text.rs
+++ b/dhall/src/syntax/ast/text.rs
diff --git a/dhall/src/syntax/core/visitor.rs b/dhall/src/syntax/ast/visitor.rs
index b76d037..b557995 100644
--- a/dhall/src/syntax/core/visitor.rs
+++ b/dhall/src/syntax/ast/visitor.rs
@@ -1,7 +1,7 @@
 use crate::syntax::*;
 use std::iter::FromIterator;
 
-/// A visitor trait that can be used to traverse `ExprF`s. We need this pattern so that Rust lets
+/// A visitor trait that can be used to traverse `ExprKind`s. We need this pattern so that Rust lets
 /// us have as much mutability as we can.
 /// For example, `traverse_ref_with_special_handling_of_binders` cannot be made using only
 /// `traverse_ref`, because `traverse_ref` takes a `FnMut` so we would need to pass multiple
@@ -9,7 +9,7 @@ use std::iter::FromIterator;
 /// preventing exactly this ! So we have to be more clever. The visitor pattern allows us to have
 /// only one mutable thing the whole time: the visitor itself. The visitor can then carry around
 /// multiple closures or just one, and Rust is ok with either. See for example TraverseRefVisitor.
-pub trait ExprFVisitor<'a, SE1, SE2, E1, E2>: Sized {
+pub trait ExprKindVisitor<'a, SE1, SE2, E1, E2>: Sized {
     type Error;
 
     fn visit_subexpr(&mut self, subexpr: &'a SE1) -> Result<SE2, Self::Error>;
@@ -25,14 +25,14 @@ pub trait ExprFVisitor<'a, SE1, SE2, E1, E2>: Sized {
 
     fn visit(
         self,
-        input: &'a ExprF<SE1, E1>,
-    ) -> Result<ExprF<SE2, E2>, Self::Error> {
+        input: &'a ExprKind<SE1, E1>,
+    ) -> Result<ExprKind<SE2, E2>, Self::Error> {
         visit_ref(self, input)
     }
 }
 
-/// Like `ExprFVisitor`, but by mutable reference
-pub trait ExprFMutVisitor<'a, SE, E>: Sized {
+/// Like `ExprKindVisitor`, but by mutable reference
+pub trait ExprKindMutVisitor<'a, SE, E>: Sized {
     type Error;
 
     fn visit_subexpr(&mut self, subexpr: &'a mut SE)
@@ -49,17 +49,17 @@ pub trait ExprFMutVisitor<'a, SE, E>: Sized {
         self.visit_subexpr(subexpr)
     }
 
-    fn visit(self, input: &'a mut ExprF<SE, E>) -> Result<(), Self::Error> {
+    fn visit(self, input: &'a mut ExprKind<SE, E>) -> Result<(), Self::Error> {
         visit_mut(self, input)
     }
 }
 
 fn visit_ref<'a, V, SE1, SE2, E1, E2>(
     mut v: V,
-    input: &'a ExprF<SE1, E1>,
-) -> Result<ExprF<SE2, E2>, V::Error>
+    input: &'a ExprKind<SE1, E1>,
+) -> Result<ExprKind<SE2, E2>, V::Error>
 where
-    V: ExprFVisitor<'a, SE1, SE2, E1, E2>,
+    V: ExprKindVisitor<'a, SE1, SE2, E1, E2>,
 {
     fn vec<'a, T, U, Err, F: FnMut(&'a T) -> Result<U, Err>>(
         x: &'a [T],
@@ -83,7 +83,7 @@ where
     where
         SE1: 'a,
         T: FromIterator<(Label, SE2)>,
-        V: ExprFVisitor<'a, SE1, SE2, E1, E2>,
+        V: ExprKindVisitor<'a, SE1, SE2, E1, E2>,
     {
         x.into_iter()
             .map(|(k, x)| Ok((k.clone(), v.visit_subexpr(x)?)))
@@ -96,7 +96,7 @@ where
     where
         SE1: 'a,
         T: FromIterator<(Label, Option<SE2>)>,
-        V: ExprFVisitor<'a, SE1, SE2, E1, E2>,
+        V: ExprKindVisitor<'a, SE1, SE2, E1, E2>,
     {
         x.into_iter()
             .map(|(k, x)| {
@@ -111,7 +111,7 @@ where
             .collect()
     }
 
-    use crate::syntax::ExprF::*;
+    use crate::syntax::ExprKind::*;
     Ok(match input {
         Var(v) => Var(v.clone()),
         Lam(l, t, e) => {
@@ -172,14 +172,14 @@ where
 
 fn visit_mut<'a, V, SE, E>(
     mut v: V,
-    input: &'a mut ExprF<SE, E>,
+    input: &'a mut ExprKind<SE, E>,
 ) -> Result<(), V::Error>
 where
-    V: ExprFMutVisitor<'a, SE, E>,
+    V: ExprKindMutVisitor<'a, SE, E>,
 {
     fn vec<'a, V, SE, E>(v: &mut V, x: &'a mut Vec<SE>) -> Result<(), V::Error>
     where
-        V: ExprFMutVisitor<'a, SE, E>,
+        V: ExprKindMutVisitor<'a, SE, E>,
     {
         for x in x {
             v.visit_subexpr(x)?;
@@ -191,7 +191,7 @@ where
         x: &'a mut Option<SE>,
     ) -> Result<(), V::Error>
     where
-        V: ExprFMutVisitor<'a, SE, E>,
+        V: ExprKindMutVisitor<'a, SE, E>,
     {
         if let Some(x) = x {
             v.visit_subexpr(x)?;
@@ -204,7 +204,7 @@ where
     ) -> Result<(), V::Error>
     where
         SE: 'a,
-        V: ExprFMutVisitor<'a, SE, E>,
+        V: ExprKindMutVisitor<'a, SE, E>,
     {
         for (_, x) in x {
             v.visit_subexpr(x)?;
@@ -217,7 +217,7 @@ where
     ) -> Result<(), V::Error>
     where
         SE: 'a,
-        V: ExprFMutVisitor<'a, SE, E>,
+        V: ExprKindMutVisitor<'a, SE, E>,
     {
         for (_, x) in x {
             opt(&mut v, x)?;
@@ -225,7 +225,7 @@ where
         Ok(())
     }
 
-    use crate::syntax::ExprF::*;
+    use crate::syntax::ExprKind::*;
     match input {
         Var(_) | Const(_) | Builtin(_) | BoolLit(_) | NaturalLit(_)
         | IntegerLit(_) | DoubleLit(_) => {}
@@ -293,7 +293,7 @@ pub struct TraverseRefWithBindersVisitor<F1, F2> {
     pub visit_under_binder: F2,
 }
 
-impl<'a, SE, E, SE2, Err, F1, F2> ExprFVisitor<'a, SE, SE2, E, E>
+impl<'a, SE, E, SE2, Err, F1, F2> ExprKindVisitor<'a, SE, SE2, E, E>
     for TraverseRefWithBindersVisitor<F1, F2>
 where
     SE: 'a,
@@ -322,7 +322,7 @@ pub struct TraverseRefVisitor<F1> {
     pub visit_subexpr: F1,
 }
 
-impl<'a, SE, E, SE2, Err, F1> ExprFVisitor<'a, SE, SE2, E, E>
+impl<'a, SE, E, SE2, Err, F1> ExprKindVisitor<'a, SE, SE2, E, E>
     for TraverseRefVisitor<F1>
 where
     SE: 'a,
@@ -343,7 +343,8 @@ pub struct TraverseMutVisitor<F1> {
     pub visit_subexpr: F1,
 }
 
-impl<'a, SE, E, Err, F1> ExprFMutVisitor<'a, SE, E> for TraverseMutVisitor<F1>
+impl<'a, SE, E, Err, F1> ExprKindMutVisitor<'a, SE, E>
+    for TraverseMutVisitor<F1>
 where
     SE: 'a,
     E: 'a,
diff --git a/dhall/src/syntax/binary/decode.rs b/dhall/src/syntax/binary/decode.rs
index 46c9921..254ab07 100644
--- a/dhall/src/syntax/binary/decode.rs
+++ b/dhall/src/syntax/binary/decode.rs
@@ -2,12 +2,13 @@ use itertools::Itertools;
 use serde_cbor::value::value as cbor;
 use std::iter::FromIterator;
 
-use crate::semantics::error::DecodeError;
+use crate::error::DecodeError;
 use crate::semantics::phase::DecodedExpr;
 use crate::syntax;
 use crate::syntax::{
-    Expr, ExprF, FilePath, FilePrefix, Hash, ImportLocation, ImportMode,
-    Integer, InterpolatedText, Label, Natural, RawExpr, Scheme, Span, URL, V,
+    Expr, ExprKind, FilePath, FilePrefix, Hash, ImportLocation, ImportMode,
+    Integer, InterpolatedText, Label, Natural, Scheme, Span, UnspannedExpr,
+    URL, V,
 };
 
 pub(crate) fn decode(data: &[u8]) -> Result<DecodedExpr, DecodeError> {
@@ -18,17 +19,17 @@ pub(crate) fn decode(data: &[u8]) -> Result<DecodedExpr, DecodeError> {
 }
 
 // Should probably rename this
-fn rc<E>(x: RawExpr<E>) -> Expr<E> {
+fn rc<E>(x: UnspannedExpr<E>) -> Expr<E> {
     Expr::new(x, Span::Decoded)
 }
 
 fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
     use cbor::Value::*;
     use syntax::{BinOp, Builtin, Const};
-    use ExprF::*;
+    use ExprKind::*;
     Ok(rc(match data {
         String(s) => match Builtin::parse(s) {
-            Some(b) => ExprF::Builtin(b),
+            Some(b) => ExprKind::Builtin(b),
             None => match s.as_str() {
                 "True" => BoolLit(true),
                 "False" => BoolLit(false),
@@ -123,7 +124,7 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
             }
             [U64(4), t] => {
                 let t = cbor_value_to_dhall(&t)?;
-                EmptyListLit(rc(App(rc(ExprF::Builtin(Builtin::List)), t)))
+                EmptyListLit(rc(App(rc(ExprKind::Builtin(Builtin::List)), t)))
             }
             [U64(4), Null, rest @ ..] => {
                 let rest = rest
@@ -139,14 +140,14 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
             // Old-style optional literals
             [U64(5), t] => {
                 let t = cbor_value_to_dhall(&t)?;
-                App(rc(ExprF::Builtin(Builtin::OptionalNone)), t)
+                App(rc(ExprKind::Builtin(Builtin::OptionalNone)), t)
             }
             [U64(5), t, x] => {
                 let x = cbor_value_to_dhall(&x)?;
                 let t = cbor_value_to_dhall(&t)?;
                 Annot(
                     rc(SomeLit(x)),
-                    rc(App(rc(ExprF::Builtin(Builtin::Optional)), t)),
+                    rc(App(rc(ExprKind::Builtin(Builtin::Optional)), t)),
                 )
             }
             [U64(6), x, y] => {
diff --git a/dhall/src/syntax/binary/encode.rs b/dhall/src/syntax/binary/encode.rs
index 8e13efd..25a545c 100644
--- a/dhall/src/syntax/binary/encode.rs
+++ b/dhall/src/syntax/binary/encode.rs
@@ -1,12 +1,12 @@
 use serde_cbor::value::value as cbor;
 use std::vec;
 
-use crate::semantics::error::EncodeError;
+use crate::error::EncodeError;
 use crate::syntax;
 use crate::syntax::map::DupTreeMap;
 use crate::syntax::{
-    Expr, ExprF, FilePrefix, Hash, Import, ImportLocation, ImportMode, Label,
-    Scheme, V,
+    Expr, ExprKind, FilePrefix, Hash, Import, ImportLocation, ImportMode,
+    Label, Scheme, V,
 };
 
 /// Warning: will fail if `expr` contains an `Embed` node.
@@ -46,7 +46,7 @@ where
     use cbor::Value::{String, I64, U64};
     use std::iter::once;
     use syntax::Builtin;
-    use syntax::ExprF::*;
+    use syntax::ExprKind::*;
 
     use self::Serialize::{RecordMap, UnionMap};
     fn expr<E>(x: &Expr<E>) -> self::Serialize<'_, E> {
@@ -110,7 +110,9 @@ where
         SomeLit(x) => ser_seq!(ser; tag(5), null(), expr(x)),
         EmptyListLit(x) => match x.as_ref() {
             App(f, a) => match f.as_ref() {
-                ExprF::Builtin(Builtin::List) => ser_seq!(ser; tag(4), expr(a)),
+                ExprKind::Builtin(Builtin::List) => {
+                    ser_seq!(ser; tag(4), expr(a))
+                }
                 _ => ser_seq!(ser; tag(28), expr(x)),
             },
             _ => ser_seq!(ser; tag(28), expr(x)),
@@ -284,7 +286,7 @@ fn collect_nested_applications<'a, E>(
 ) -> (&'a Expr<E>, Vec<&'a Expr<E>>) {
     fn go<'a, E>(e: &'a Expr<E>, vec: &mut Vec<&'a Expr<E>>) -> &'a Expr<E> {
         match e.as_ref() {
-            ExprF::App(f, a) => {
+            ExprKind::App(f, a) => {
                 vec.push(a);
                 go(f, vec)
             }
@@ -306,7 +308,7 @@ fn collect_nested_lets<'a, E>(
         vec: &mut Vec<LetBinding<'a, E>>,
     ) -> &'a Expr<E> {
         match e.as_ref() {
-            ExprF::Let(l, t, v, e) => {
+            ExprKind::Let(l, t, v, e) => {
                 vec.push((l, t, v));
                 go(e, vec)
             }
diff --git a/dhall/src/syntax/core/context.rs b/dhall/src/syntax/core/context.rs
deleted file mode 100644
index 6844baa..0000000
--- a/dhall/src/syntax/core/context.rs
+++ /dev/null
@@ -1,80 +0,0 @@
-use std::cmp::Eq;
-use std::collections::HashMap;
-use std::hash::Hash;
-
-/// A `(Context a)` associates `Text` labels with values of type `a`
-///
-/// The `Context` is used for type-checking when `(a = Expr)`
-///
-/// * You create a `Context` using `empty` and `insert`
-/// * You transform a `Context` using `fmap`
-/// * You consume a `Context` using `lookup` and `toList`
-///
-/// The difference between a `Context` and a `Map` is that a `Context` lets you
-/// have multiple ordered occurrences of the same key and you can query for the
-/// `n`th occurrence of a given key.
-///
-#[derive(Debug, Clone)]
-pub struct Context<K: Eq + Hash, T>(HashMap<K, Vec<T>>);
-
-impl<K: Hash + Eq + Clone, T> Context<K, T> {
-    /// An empty context with no key-value pairs
-    pub fn new() -> Self {
-        Context(HashMap::new())
-    }
-
-    /// Look up a key by name and index
-    ///
-    /// ```c
-    /// lookup _ _         empty  = Nothing
-    /// lookup k 0 (insert k v c) = Just v
-    /// lookup k n (insert k v c) = lookup k (n - 1) c  -- 1 <= n
-    /// lookup k n (insert j v c) = lookup k  n      c  -- k /= j
-    /// ```
-    pub fn lookup<'a>(&'a self, k: &K, n: usize) -> Option<&'a T> {
-        self.0.get(k).and_then(|v| {
-            if n < v.len() {
-                v.get(v.len() - 1 - n)
-            } else {
-                None
-            }
-        })
-    }
-
-    pub fn map<U, F: Fn(&K, &T) -> U>(&self, f: F) -> Context<K, U> {
-        Context(
-            self.0
-                .iter()
-                .map(|(k, vs)| {
-                    ((*k).clone(), vs.iter().map(|v| f(k, v)).collect())
-                })
-                .collect(),
-        )
-    }
-
-    pub fn lookup_all<'a>(&'a self, k: &K) -> impl Iterator<Item = &T> {
-        self.0.get(k).into_iter().flat_map(|v| v.iter())
-    }
-
-    pub fn iter(&self) -> impl Iterator<Item = (&K, &T)> {
-        self.0
-            .iter()
-            .flat_map(|(k, vs)| vs.iter().map(move |v| (k, v)))
-    }
-
-    pub fn iter_keys(&self) -> impl Iterator<Item = (&K, &Vec<T>)> {
-        self.0.iter()
-    }
-}
-
-impl<K: Hash + Eq + Clone, T: Clone> Context<K, T> {
-    /// Add a key-value pair to the `Context`
-    pub fn insert(&self, k: K, v: T) -> Self {
-        let mut ctx = (*self).clone();
-        {
-            let m = ctx.0.entry(k).or_insert_with(Vec::new);
-            m.push(v);
-        }
-        ctx
-    }
-}
diff --git a/dhall/src/syntax/mod.rs b/dhall/src/syntax/mod.rs
index a82e827..512a026 100644
--- a/dhall/src/syntax/mod.rs
+++ b/dhall/src/syntax/mod.rs
@@ -5,10 +5,9 @@
     clippy::type_complexity
 )]
 
-mod core;
-pub use crate::syntax::core::context;
-pub use crate::syntax::core::visitor;
-pub use crate::syntax::core::*;
+mod ast;
+pub use crate::syntax::ast::visitor;
+pub use crate::syntax::ast::*;
 pub use crate::syntax::text::parser::*;
 pub use crate::syntax::text::printer::*;
 pub mod binary;
diff --git a/dhall/src/syntax/text/parser.rs b/dhall/src/syntax/text/parser.rs
index f6b6577..90cb4b1 100644
--- a/dhall/src/syntax/text/parser.rs
+++ b/dhall/src/syntax/text/parser.rs
@@ -7,13 +7,12 @@ use pest_consume::{match_nodes, Parser};
 
 use crate::semantics::phase::Normalized;
 use crate::syntax;
-use crate::syntax::core;
 use crate::syntax::map::{DupTreeMap, DupTreeSet};
-use crate::syntax::ExprF::*;
+use crate::syntax::ExprKind::*;
 use crate::syntax::{
-    FilePath, FilePrefix, Hash, ImportLocation, ImportMode, InterpolatedText,
-    InterpolatedTextContents, Label, NaiveDouble, RawExpr, Scheme, Span, URL,
-    V,
+    Double, FilePath, FilePrefix, Hash, ImportLocation, ImportMode, Integer,
+    InterpolatedText, InterpolatedTextContents, Label, NaiveDouble, Natural,
+    Scheme, Span, UnspannedExpr, URL, V,
 };
 
 // This file consumes the parse tree generated by pest and turns it into
@@ -77,10 +76,14 @@ impl crate::syntax::Builtin {
 fn input_to_span(input: ParseInput) -> Span {
     Span::make(input.user_data().clone(), input.as_pair().as_span())
 }
-fn spanned(input: ParseInput, x: RawExpr<Normalized>) -> Expr {
+fn spanned(input: ParseInput, x: UnspannedExpr<Normalized>) -> Expr {
     Expr::new(x, input_to_span(input))
 }
-fn spanned_union(span1: Span, span2: Span, x: RawExpr<Normalized>) -> Expr {
+fn spanned_union(
+    span1: Span,
+    span2: Span,
+    x: UnspannedExpr<Normalized>,
+) -> Expr {
     Expr::new(x, span1.union(&span2))
 }
 
@@ -349,20 +352,20 @@ impl DhallParser {
     }
 
     #[alias(double_literal)]
-    fn NaN(_input: ParseInput) -> ParseResult<core::Double> {
+    fn NaN(_input: ParseInput) -> ParseResult<Double> {
         Ok(std::f64::NAN.into())
     }
     #[alias(double_literal)]
-    fn minus_infinity_literal(_input: ParseInput) -> ParseResult<core::Double> {
+    fn minus_infinity_literal(_input: ParseInput) -> ParseResult<Double> {
         Ok(std::f64::NEG_INFINITY.into())
     }
     #[alias(double_literal)]
-    fn plus_infinity_literal(_input: ParseInput) -> ParseResult<core::Double> {
+    fn plus_infinity_literal(_input: ParseInput) -> ParseResult<Double> {
         Ok(std::f64::INFINITY.into())
     }
 
     #[alias(double_literal)]
-    fn numeric_double_literal(input: ParseInput) -> ParseResult<core::Double> {
+    fn numeric_double_literal(input: ParseInput) -> ParseResult<Double> {
         let s = input.as_str().trim();
         match s.parse::<f64>() {
             Ok(x) if x.is_infinite() => Err(input.error(format!(
@@ -374,7 +377,7 @@ impl DhallParser {
         }
     }
 
-    fn natural_literal(input: ParseInput) -> ParseResult<core::Natural> {
+    fn natural_literal(input: ParseInput) -> ParseResult<Natural> {
         input
             .as_str()
             .trim()
@@ -382,7 +385,7 @@ impl DhallParser {
             .map_err(|e| input.error(format!("{}", e)))
     }
 
-    fn integer_literal(input: ParseInput) -> ParseResult<core::Integer> {
+    fn integer_literal(input: ParseInput) -> ParseResult<Integer> {
         input
             .as_str()
             .trim()
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index 8df456b..78942ed 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -2,10 +2,137 @@ use crate::syntax::*;
 use itertools::Itertools;
 use std::fmt::{self, Display};
 
+// There is a one-to-one correspondence between the formatter and the grammar. Each phase is
+// named after a corresponding grammar group, and the structure of the formatter reflects
+// the relationship between the corresponding grammar rules. This leads to the nice property
+// of automatically getting all the parentheses and precedences right.
+#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+enum PrintPhase {
+    Base,
+    Operator,
+    BinOp(ast::BinOp),
+    App,
+    Import,
+    Primitive,
+}
+
+// Wraps an Expr with a phase, so that phase selection can be done separate from the actual
+// printing.
+#[derive(Clone)]
+struct PhasedExpr<'a, E>(&'a Expr<E>, PrintPhase);
+
+impl<'a, E: Display + Clone> PhasedExpr<'a, E> {
+    fn phase(self, phase: PrintPhase) -> PhasedExpr<'a, E> {
+        PhasedExpr(self.0, phase)
+    }
+}
+
+impl<E: Display + Clone> UnspannedExpr<E> {
+    // Annotate subexpressions with the appropriate phase, defaulting to Base
+    fn annotate_with_phases<'a>(&'a self) -> ExprKind<PhasedExpr<'a, E>, E> {
+        use crate::syntax::ExprKind::*;
+        use PrintPhase::*;
+        let with_base = self.map_ref(|e| PhasedExpr(e, Base));
+        match with_base {
+            Pi(a, b, c) => {
+                if &String::from(&a) == "_" {
+                    Pi(a, b.phase(Operator), c)
+                } else {
+                    Pi(a, b, c)
+                }
+            }
+            Merge(a, b, c) => Merge(
+                a.phase(PrintPhase::Import),
+                b.phase(PrintPhase::Import),
+                c.map(|x| x.phase(PrintPhase::App)),
+            ),
+            ToMap(a, b) => ToMap(
+                a.phase(PrintPhase::Import),
+                b.map(|x| x.phase(PrintPhase::App)),
+            ),
+            Annot(a, b) => Annot(a.phase(Operator), b),
+            ExprKind::BinOp(op, a, b) => ExprKind::BinOp(
+                op,
+                a.phase(PrintPhase::BinOp(op)),
+                b.phase(PrintPhase::BinOp(op)),
+            ),
+            SomeLit(e) => SomeLit(e.phase(PrintPhase::Import)),
+            ExprKind::App(f, a) => ExprKind::App(
+                f.phase(PrintPhase::Import),
+                a.phase(PrintPhase::Import),
+            ),
+            Field(a, b) => Field(a.phase(Primitive), b),
+            Projection(e, ls) => Projection(e.phase(Primitive), ls),
+            ProjectionByExpr(a, b) => ProjectionByExpr(a.phase(Primitive), b),
+            e => e,
+        }
+    }
+
+    fn fmt_phase(
+        &self,
+        f: &mut fmt::Formatter,
+        phase: PrintPhase,
+    ) -> Result<(), fmt::Error> {
+        use crate::syntax::ExprKind::*;
+
+        let needs_paren = match self {
+            Lam(_, _, _)
+            | BoolIf(_, _, _)
+            | Pi(_, _, _)
+            | Let(_, _, _, _)
+            | EmptyListLit(_)
+            | NEListLit(_)
+            | SomeLit(_)
+            | Merge(_, _, _)
+            | ToMap(_, _)
+            | Annot(_, _) => phase > PrintPhase::Base,
+            // Precedence is magically handled by the ordering of BinOps.
+            ExprKind::BinOp(op, _, _) => phase > PrintPhase::BinOp(*op),
+            ExprKind::App(_, _) => phase > PrintPhase::App,
+            Field(_, _) | Projection(_, _) | ProjectionByExpr(_, _) => {
+                phase > PrintPhase::Import
+            }
+            _ => false,
+        };
+
+        if needs_paren {
+            f.write_str("(")?;
+        }
+        self.annotate_with_phases().fmt(f)?;
+        if needs_paren {
+            f.write_str(")")?;
+        }
+
+        Ok(())
+    }
+}
+
+fn fmt_list<T, I, F>(
+    open: &str,
+    sep: &str,
+    close: &str,
+    it: I,
+    f: &mut fmt::Formatter,
+    func: F,
+) -> Result<(), fmt::Error>
+where
+    I: IntoIterator<Item = T>,
+    F: Fn(T, &mut fmt::Formatter) -> Result<(), fmt::Error>,
+{
+    f.write_str(open)?;
+    for (i, x) in it.into_iter().enumerate() {
+        if i > 0 {
+            f.write_str(sep)?;
+        }
+        func(x, f)?;
+    }
+    f.write_str(close)
+}
+
 /// Generic instance that delegates to subexpressions
-impl<SE: Display + Clone, E: Display> Display for ExprF<SE, E> {
+impl<SE: Display + Clone, E: Display> Display for ExprKind<SE, E> {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::syntax::ExprF::*;
+        use crate::syntax::ExprKind::*;
         match self {
             Lam(a, b, c) => {
                 write!(f, "λ({} : {}) → {}", a, b, c)?;
@@ -53,10 +180,10 @@ impl<SE: Display + Clone, E: Display> Display for ExprF<SE, E> {
             Assert(a) => {
                 write!(f, "assert : {}", a)?;
             }
-            ExprF::BinOp(op, a, b) => {
+            ExprKind::BinOp(op, a, b) => {
                 write!(f, "{} {} {}", a, op, b)?;
             }
-            ExprF::App(a, b) => {
+            ExprKind::App(a, b) => {
                 write!(f, "{} {}", a, b)?;
             }
             Field(a, b) => {
@@ -104,147 +231,16 @@ impl<SE: Display + Clone, E: Display> Display for ExprF<SE, E> {
     }
 }
 
-// There is a one-to-one correspondence between the formatter and the grammar. Each phase is
-// named after a corresponding grammar group, and the structure of the formatter reflects
-// the relationship between the corresponding grammar rules. This leads to the nice property
-// of automatically getting all the parentheses and precedences right.
-#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
-enum PrintPhase {
-    Base,
-    Operator,
-    BinOp(core::BinOp),
-    App,
-    Import,
-    Primitive,
-}
-
-// Wraps an Expr with a phase, so that phase selsction can be done
-// separate from the actual printing
-#[derive(Clone)]
-struct PhasedExpr<'a, A>(&'a Expr<A>, PrintPhase);
-
-impl<'a, A: Display + Clone> Display for PhasedExpr<'a, A> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        self.0.as_ref().fmt_phase(f, self.1)
-    }
-}
-
-impl<'a, A: Display + Clone> PhasedExpr<'a, A> {
-    fn phase(self, phase: PrintPhase) -> PhasedExpr<'a, A> {
-        PhasedExpr(self.0, phase)
-    }
-}
-
-impl<A: Display + Clone> RawExpr<A> {
-    fn fmt_phase(
-        &self,
-        f: &mut fmt::Formatter,
-        phase: PrintPhase,
-    ) -> Result<(), fmt::Error> {
-        use crate::syntax::ExprF::*;
-        use PrintPhase::*;
-
-        let needs_paren = match self {
-            Lam(_, _, _)
-            | BoolIf(_, _, _)
-            | Pi(_, _, _)
-            | Let(_, _, _, _)
-            | EmptyListLit(_)
-            | NEListLit(_)
-            | SomeLit(_)
-            | Merge(_, _, _)
-            | ToMap(_, _)
-            | Annot(_, _)
-                if phase > Base =>
-            {
-                true
-            }
-            // Precedence is magically handled by the ordering of BinOps.
-            ExprF::BinOp(op, _, _) if phase > PrintPhase::BinOp(*op) => true,
-            ExprF::App(_, _) if phase > PrintPhase::App => true,
-            Field(_, _) | Projection(_, _) | ProjectionByExpr(_, _)
-                if phase > PrintPhase::Import =>
-            {
-                true
-            }
-            _ => false,
-        };
-
-        // Annotate subexpressions with the appropriate phase, defaulting to Base
-        let phased_self = match self.map_ref(|e| PhasedExpr(e, Base)) {
-            Pi(a, b, c) => {
-                if &String::from(&a) == "_" {
-                    Pi(a, b.phase(Operator), c)
-                } else {
-                    Pi(a, b, c)
-                }
-            }
-            Merge(a, b, c) => Merge(
-                a.phase(PrintPhase::Import),
-                b.phase(PrintPhase::Import),
-                c.map(|x| x.phase(PrintPhase::App)),
-            ),
-            ToMap(a, b) => ToMap(
-                a.phase(PrintPhase::Import),
-                b.map(|x| x.phase(PrintPhase::App)),
-            ),
-            Annot(a, b) => Annot(a.phase(Operator), b),
-            ExprF::BinOp(op, a, b) => ExprF::BinOp(
-                op,
-                a.phase(PrintPhase::BinOp(op)),
-                b.phase(PrintPhase::BinOp(op)),
-            ),
-            SomeLit(e) => SomeLit(e.phase(PrintPhase::Import)),
-            ExprF::App(f, a) => ExprF::App(
-                f.phase(PrintPhase::Import),
-                a.phase(PrintPhase::Import),
-            ),
-            Field(a, b) => Field(a.phase(Primitive), b),
-            Projection(e, ls) => Projection(e.phase(Primitive), ls),
-            ProjectionByExpr(a, b) => ProjectionByExpr(a.phase(Primitive), b),
-            e => e,
-        };
-
-        if needs_paren {
-            f.write_str("(")?;
-        }
-
-        // Uses the ExprF<PhasedExpr<_>, _> instance
-        phased_self.fmt(f)?;
-
-        if needs_paren {
-            f.write_str(")")?;
-        }
-        Ok(())
-    }
-}
-
-impl<A: Display + Clone> Display for Expr<A> {
+impl<E: Display + Clone> Display for Expr<E> {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
         self.as_ref().fmt_phase(f, PrintPhase::Base)
     }
 }
 
-fn fmt_list<T, I, F>(
-    open: &str,
-    sep: &str,
-    close: &str,
-    it: I,
-    f: &mut fmt::Formatter,
-    func: F,
-) -> Result<(), fmt::Error>
-where
-    I: IntoIterator<Item = T>,
-    F: Fn(T, &mut fmt::Formatter) -> Result<(), fmt::Error>,
-{
-    f.write_str(open)?;
-    for (i, x) in it.into_iter().enumerate() {
-        if i > 0 {
-            f.write_str(sep)?;
-        }
-        func(x, f)?;
+impl<'a, E: Display + Clone> Display for PhasedExpr<'a, E> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        self.0.as_ref().fmt_phase(f, self.1)
     }
-    f.write_str(close)
 }
 
 impl<SubExpr: Display> Display for InterpolatedText<SubExpr> {
@@ -361,6 +357,7 @@ impl Display for Hash {
         }
     }
 }
+
 impl<SubExpr: Display> Display for Import<SubExpr> {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
         use FilePrefix::*;