Cleanup variable handling

2 files changed, 25 insertions, 11 deletions

diff --git a/dhall/src/semantics/tck/env.rs b/dhall/src/semantics/tck/env.rs
index 32c2f21..1276a48 100644
--- a/dhall/src/semantics/tck/env.rs
+++ b/dhall/src/semantics/tck/env.rs
@@ -37,7 +37,7 @@ impl VarEnv {
     }
     pub fn lookup_fallible(&self, var: &NzVar) -> Option<AlphaVar> {
         let idx = self.size.checked_sub(var.idx() + 1)?;
-        Some(AlphaVar::new(V((), idx)))
+        Some(AlphaVar::new(idx))
     }
 }
 
@@ -68,7 +68,7 @@ impl NameEnv {
         self.names.pop();
     }
 
-    pub fn unlabel_var(&self, var: &V<Label>) -> Option<AlphaVar> {
+    pub fn unlabel_var(&self, var: &V) -> Option<AlphaVar> {
         let V(name, idx) = var;
         let (idx, _) = self
             .names
@@ -77,9 +77,9 @@ impl NameEnv {
             .enumerate()
             .filter(|(_, n)| *n == name)
             .nth(*idx)?;
-        Some(AlphaVar::new(V((), idx)))
+        Some(AlphaVar::new(idx))
     }
-    pub fn label_var(&self, var: &AlphaVar) -> V<Label> {
+    pub fn label_var(&self, var: &AlphaVar) -> V {
         let name = &self.names[self.names.len() - 1 - var.idx()];
         let idx = self
             .names
@@ -129,7 +129,7 @@ impl TyEnv {
             items: self.items.insert_value(e),
         }
     }
-    pub fn lookup(&self, var: &V<Label>) -> Option<(TyExprKind, Type)> {
+    pub fn lookup(&self, var: &V) -> Option<(TyExprKind, Type)> {
         let var = self.names.unlabel_var(var)?;
         let ty = self.items.lookup_val(&var).get_type().unwrap();
         Some((TyExprKind::Var(var), ty))
diff --git a/dhall/src/semantics/tck/tyexpr.rs b/dhall/src/semantics/tck/tyexpr.rs
index 262cda6..114bb14 100644
--- a/dhall/src/semantics/tck/tyexpr.rs
+++ b/dhall/src/semantics/tck/tyexpr.rs
@@ -1,5 +1,4 @@
 use crate::error::{TypeError, TypeMessage};
-use crate::semantics::core::var::AlphaVar;
 use crate::semantics::phase::normalize::normalize_tyexpr_whnf;
 use crate::semantics::phase::typecheck::rc;
 use crate::semantics::phase::Normalized;
@@ -9,6 +8,19 @@ use crate::syntax::{ExprKind, Span, V};
 
 pub(crate) type Type = Value;
 
+/// Stores an alpha-normalized variable.
+#[derive(Debug, Clone, Copy)]
+pub struct AlphaVar {
+    idx: usize,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum TyExprKind {
+    Var(AlphaVar),
+    // Forbidden ExprKind variants: Var, Import, Embed
+    Expr(ExprKind<TyExpr, Normalized>),
+}
+
 // An expression with inferred types at every node and resolved variables.
 #[derive(Clone)]
 pub(crate) struct TyExpr {
@@ -17,11 +29,13 @@ pub(crate) struct TyExpr {
     span: Span,
 }
 
-#[derive(Debug, Clone)]
-pub(crate) enum TyExprKind {
-    Var(AlphaVar),
-    // Forbidden ExprKind variants: Var, Import, Embed
-    Expr(ExprKind<TyExpr, Normalized>),
+impl AlphaVar {
+    pub(crate) fn new(idx: usize) -> Self {
+        AlphaVar { idx }
+    }
+    pub(crate) fn idx(&self) -> usize {
+        self.idx
+    }
 }
 
 impl TyExpr {