Move envs to their own files

11 files changed, 239 insertions, 241 deletions

diff --git a/dhall/src/semantics/core/value.rs b/dhall/src/semantics/core/value.rs
index 90b30b4..7334552 100644
--- a/dhall/src/semantics/core/value.rs
+++ b/dhall/src/semantics/core/value.rs
@@ -4,12 +4,12 @@ use std::rc::Rc;
 
 use crate::error::{TypeError, TypeMessage};
 use crate::semantics::core::var::{AlphaVar, Binder};
-use crate::semantics::nze::{NzVar, VarEnv};
-use crate::semantics::phase::normalize::{apply_any, normalize_whnf, NzEnv};
+use crate::semantics::phase::normalize::{apply_any, normalize_whnf};
 use crate::semantics::phase::typecheck::{
     builtin_to_value, builtin_to_value_env, const_to_value,
 };
 use crate::semantics::phase::{Normalized, NormalizedExpr, ToExprOptions};
+use crate::semantics::{NzEnv, NzVar, VarEnv};
 use crate::semantics::{TyExpr, TyExprKind};
 use crate::syntax::{
     BinOp, Builtin, Const, ExprKind, Integer, InterpolatedTextContents, Label,
diff --git a/dhall/src/semantics/mod.rs b/dhall/src/semantics/mod.rs
index 1304502..ce08334 100644
--- a/dhall/src/semantics/mod.rs
+++ b/dhall/src/semantics/mod.rs
@@ -3,4 +3,5 @@ pub mod nze;
 pub mod phase;
 pub mod tck;
 pub(crate) use self::core::*;
+pub(crate) use self::nze::*;
 pub(crate) use self::tck::*;
diff --git a/dhall/src/semantics/nze/env.rs b/dhall/src/semantics/nze/env.rs
new file mode 100644
index 0000000..203d99a
--- /dev/null
+++ b/dhall/src/semantics/nze/env.rs
@@ -0,0 +1,87 @@
+use crate::semantics::{AlphaVar, TyEnv, Value, ValueKind};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum NzVar {
+    /// Reverse-debruijn index: counts number of binders from the bottom of the stack.
+    Bound(usize),
+    /// Fake fresh variable generated for expression equality checking.
+    Fresh(usize),
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum NzEnvItem {
+    // Variable is bound with given type
+    Kept(Value),
+    // Variable has been replaced by corresponding value
+    Replaced(Value),
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct NzEnv {
+    items: Vec<NzEnvItem>,
+}
+
+impl NzVar {
+    pub fn new(idx: usize) -> Self {
+        NzVar::Bound(idx)
+    }
+    pub fn fresh() -> Self {
+        use std::sync::atomic::{AtomicUsize, Ordering};
+        // Global counter to ensure uniqueness of the generated id.
+        static FRESH_VAR_COUNTER: AtomicUsize = AtomicUsize::new(0);
+        let id = FRESH_VAR_COUNTER.fetch_add(1, Ordering::SeqCst);
+        NzVar::Fresh(id)
+    }
+    /// Get index of bound variable.
+    /// Panics on a fresh variable.
+    pub fn idx(&self) -> usize {
+        match self {
+            NzVar::Bound(i) => *i,
+            NzVar::Fresh(_) => panic!(
+                "Trying to use a fresh variable outside of equality checking"
+            ),
+        }
+    }
+}
+
+impl NzEnv {
+    pub fn new() -> Self {
+        NzEnv { items: Vec::new() }
+    }
+    pub fn to_alpha_tyenv(&self) -> TyEnv {
+        TyEnv::from_nzenv_alpha(self)
+    }
+
+    pub fn insert_type(&self, t: Value) -> Self {
+        let mut env = self.clone();
+        env.items.push(NzEnvItem::Kept(t));
+        env
+    }
+    pub fn insert_value(&self, e: Value) -> Self {
+        let mut env = self.clone();
+        env.items.push(NzEnvItem::Replaced(e));
+        env
+    }
+    pub fn lookup_val(&self, var: &AlphaVar) -> Value {
+        let idx = self.items.len() - 1 - var.idx();
+        match &self.items[idx] {
+            NzEnvItem::Kept(ty) => Value::from_kind_and_type_whnf(
+                ValueKind::Var(var.clone(), NzVar::new(idx)),
+                ty.clone(),
+            ),
+            NzEnvItem::Replaced(x) => x.clone(),
+        }
+    }
+
+    pub fn size(&self) -> usize {
+        self.items.len()
+    }
+}
+
+/// Ignore NzEnv when comparing; useful because we store them in `AppliedBuiltin`.
+impl std::cmp::PartialEq for NzEnv {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+impl std::cmp::Eq for NzEnv {}
diff --git a/dhall/src/semantics/nze/mod.rs b/dhall/src/semantics/nze/mod.rs
index 213404c..1cd2363 100644
--- a/dhall/src/semantics/nze/mod.rs
+++ b/dhall/src/semantics/nze/mod.rs
@@ -1,2 +1,2 @@
-pub mod nzexpr;
-pub(crate) use nzexpr::*;
+pub mod env;
+pub(crate) use env::*;
diff --git a/dhall/src/semantics/nze/nzexpr.rs b/dhall/src/semantics/nze/nzexpr.rs
deleted file mode 100644
index c065a5b..0000000
--- a/dhall/src/semantics/nze/nzexpr.rs
+++ /dev/null
@@ -1,116 +0,0 @@
-use crate::semantics::core::var::AlphaVar;
-use crate::syntax::{Label, V};
-
-pub(crate) type Binder = Label;
-
-#[derive(Debug, Clone)]
-pub(crate) struct NameEnv {
-    names: Vec<Binder>,
-}
-
-#[derive(Debug, Clone, Copy)]
-pub(crate) struct VarEnv {
-    size: usize,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) enum NzVar {
-    /// Reverse-debruijn index: counts number of binders from the bottom of the stack.
-    Bound(usize),
-    /// Fake fresh variable generated for expression equality checking.
-    Fresh(usize),
-}
-
-impl NameEnv {
-    pub fn new() -> Self {
-        NameEnv { names: Vec::new() }
-    }
-    pub fn from_binders(names: impl Iterator<Item = Binder>) -> Self {
-        NameEnv {
-            names: names.collect(),
-        }
-    }
-    pub fn as_varenv(&self) -> VarEnv {
-        VarEnv {
-            size: self.names.len(),
-        }
-    }
-
-    pub fn insert(&self, x: &Binder) -> Self {
-        let mut env = self.clone();
-        env.insert_mut(x);
-        env
-    }
-    pub fn insert_mut(&mut self, x: &Binder) {
-        self.names.push(x.clone())
-    }
-    pub fn remove_mut(&mut self) {
-        self.names.pop();
-    }
-
-    pub fn unlabel_var(&self, var: &V<Binder>) -> Option<AlphaVar> {
-        let V(name, idx) = var;
-        let (idx, _) = self
-            .names
-            .iter()
-            .rev()
-            .enumerate()
-            .filter(|(_, n)| *n == name)
-            .nth(*idx)?;
-        Some(AlphaVar::new(V((), idx)))
-    }
-    pub fn label_var(&self, var: &AlphaVar) -> V<Binder> {
-        let name = &self.names[self.names.len() - 1 - var.idx()];
-        let idx = self
-            .names
-            .iter()
-            .rev()
-            .take(var.idx())
-            .filter(|n| *n == name)
-            .count();
-        V(name.clone(), idx)
-    }
-}
-
-impl VarEnv {
-    pub fn new() -> Self {
-        VarEnv { size: 0 }
-    }
-    pub fn size(&self) -> usize {
-        self.size
-    }
-    pub fn insert(&self) -> Self {
-        VarEnv {
-            size: self.size + 1,
-        }
-    }
-    pub fn lookup(&self, var: &NzVar) -> AlphaVar {
-        self.lookup_fallible(var).unwrap()
-    }
-    pub fn lookup_fallible(&self, var: &NzVar) -> Option<AlphaVar> {
-        let idx = self.size.checked_sub(var.idx() + 1)?;
-        Some(AlphaVar::new(V((), idx)))
-    }
-}
-
-impl NzVar {
-    pub fn new(idx: usize) -> Self {
-        NzVar::Bound(idx)
-    }
-    pub fn fresh() -> Self {
-        use std::sync::atomic::{AtomicUsize, Ordering};
-        // Global counter to ensure uniqueness of the generated id.
-        static FRESH_VAR_COUNTER: AtomicUsize = AtomicUsize::new(0);
-        let id = FRESH_VAR_COUNTER.fetch_add(1, Ordering::SeqCst);
-        NzVar::Fresh(id)
-    }
-    // Panics on a fresh variable.
-    pub fn idx(&self) -> usize {
-        match self {
-            NzVar::Bound(i) => *i,
-            NzVar::Fresh(_) => panic!(
-                "Trying to use a fresh variable outside of equality checking"
-            ),
-        }
-    }
-}
diff --git a/dhall/src/semantics/phase/normalize.rs b/dhall/src/semantics/phase/normalize.rs
index fa80b6e..ce37993 100644
--- a/dhall/src/semantics/phase/normalize.rs
+++ b/dhall/src/semantics/phase/normalize.rs
@@ -1,16 +1,13 @@
 use std::collections::HashMap;
 use std::convert::TryInto;
 
-use crate::semantics::nze::NzVar;
 use crate::semantics::phase::typecheck::{
     builtin_to_value_env, const_to_value, rc,
 };
 use crate::semantics::phase::Normalized;
 use crate::semantics::tck::typecheck::type_with;
-use crate::semantics::tck::typecheck::TyEnv;
-use crate::semantics::{
-    AlphaVar, Binder, Closure, TyExpr, TyExprKind, Value, ValueKind,
-};
+use crate::semantics::NzEnv;
+use crate::semantics::{Binder, Closure, TyExpr, TyExprKind, Value, ValueKind};
 use crate::syntax;
 use crate::syntax::Const::Type;
 use crate::syntax::{
@@ -838,53 +835,6 @@ pub(crate) fn normalize_whnf(
     }
 }
 
-#[derive(Debug, Clone)]
-pub(crate) enum NzEnvItem {
-    // Variable is bound with given type
-    Kept(Value),
-    // Variable has been replaced by corresponding value
-    Replaced(Value),
-}
-
-#[derive(Debug, Clone)]
-pub(crate) struct NzEnv {
-    items: Vec<NzEnvItem>,
-}
-
-impl NzEnv {
-    pub fn new() -> Self {
-        NzEnv { items: Vec::new() }
-    }
-    pub fn to_alpha_tyenv(&self) -> TyEnv {
-        TyEnv::from_nzenv_alpha(self)
-    }
-
-    pub fn insert_type(&self, t: Value) -> Self {
-        let mut env = self.clone();
-        env.items.push(NzEnvItem::Kept(t));
-        env
-    }
-    pub fn insert_value(&self, e: Value) -> Self {
-        let mut env = self.clone();
-        env.items.push(NzEnvItem::Replaced(e));
-        env
-    }
-    pub fn lookup_val(&self, var: &AlphaVar) -> Value {
-        let idx = self.items.len() - 1 - var.idx();
-        match &self.items[idx] {
-            NzEnvItem::Kept(ty) => Value::from_kind_and_type_whnf(
-                ValueKind::Var(var.clone(), NzVar::new(idx)),
-                ty.clone(),
-            ),
-            NzEnvItem::Replaced(x) => x.clone(),
-        }
-    }
-
-    pub fn size(&self) -> usize {
-        self.items.len()
-    }
-}
-
 /// Normalize a TyExpr into WHNF
 pub(crate) fn normalize_tyexpr_whnf(tye: &TyExpr, env: &NzEnv) -> Value {
     let ty = match tye.get_type() {
@@ -924,11 +874,3 @@ pub(crate) fn normalize_tyexpr_whnf(tye: &TyExpr, env: &NzEnv) -> Value {
     // dbg!(tye.kind(), env, &kind);
     Value::from_kind_and_type_whnf(kind, ty)
 }
-
-/// Ignore NzEnv when comparing
-impl std::cmp::PartialEq for NzEnv {
-    fn eq(&self, _other: &Self) -> bool {
-        true
-    }
-}
-impl std::cmp::Eq for NzEnv {}
diff --git a/dhall/src/semantics/phase/typecheck.rs b/dhall/src/semantics/phase/typecheck.rs
index 4392365..2e22ad2 100644
--- a/dhall/src/semantics/phase/typecheck.rs
+++ b/dhall/src/semantics/phase/typecheck.rs
@@ -1,5 +1,4 @@
-use crate::semantics::phase::normalize::NzEnv;
-use crate::semantics::{Value, ValueKind};
+use crate::semantics::{NzEnv, Value, ValueKind};
 use crate::syntax;
 use crate::syntax::{
     Builtin, Const, Expr, ExprKind, Label, Span, UnspannedExpr,
diff --git a/dhall/src/semantics/tck/env.rs b/dhall/src/semantics/tck/env.rs
new file mode 100644
index 0000000..32c2f21
--- /dev/null
+++ b/dhall/src/semantics/tck/env.rs
@@ -0,0 +1,137 @@
+use crate::semantics::{AlphaVar, NzEnv, NzVar, TyExprKind, Type, Value};
+use crate::syntax::{Label, V};
+
+/// Environment for indexing variables.
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct VarEnv {
+    size: usize,
+}
+
+/// Environment for resolving names.
+#[derive(Debug, Clone)]
+pub(crate) struct NameEnv {
+    names: Vec<Label>,
+}
+
+/// Environment for typing expressions.
+#[derive(Debug, Clone)]
+pub(crate) struct TyEnv {
+    names: NameEnv,
+    items: NzEnv,
+}
+
+impl VarEnv {
+    pub fn new() -> Self {
+        VarEnv { size: 0 }
+    }
+    pub fn size(&self) -> usize {
+        self.size
+    }
+    pub fn insert(&self) -> Self {
+        VarEnv {
+            size: self.size + 1,
+        }
+    }
+    pub fn lookup(&self, var: &NzVar) -> AlphaVar {
+        self.lookup_fallible(var).unwrap()
+    }
+    pub fn lookup_fallible(&self, var: &NzVar) -> Option<AlphaVar> {
+        let idx = self.size.checked_sub(var.idx() + 1)?;
+        Some(AlphaVar::new(V((), idx)))
+    }
+}
+
+impl NameEnv {
+    pub fn new() -> Self {
+        NameEnv { names: Vec::new() }
+    }
+    pub fn from_binders(names: impl Iterator<Item = Label>) -> Self {
+        NameEnv {
+            names: names.collect(),
+        }
+    }
+    pub fn as_varenv(&self) -> VarEnv {
+        VarEnv {
+            size: self.names.len(),
+        }
+    }
+
+    pub fn insert(&self, x: &Label) -> Self {
+        let mut env = self.clone();
+        env.insert_mut(x);
+        env
+    }
+    pub fn insert_mut(&mut self, x: &Label) {
+        self.names.push(x.clone())
+    }
+    pub fn remove_mut(&mut self) {
+        self.names.pop();
+    }
+
+    pub fn unlabel_var(&self, var: &V<Label>) -> Option<AlphaVar> {
+        let V(name, idx) = var;
+        let (idx, _) = self
+            .names
+            .iter()
+            .rev()
+            .enumerate()
+            .filter(|(_, n)| *n == name)
+            .nth(*idx)?;
+        Some(AlphaVar::new(V((), idx)))
+    }
+    pub fn label_var(&self, var: &AlphaVar) -> V<Label> {
+        let name = &self.names[self.names.len() - 1 - var.idx()];
+        let idx = self
+            .names
+            .iter()
+            .rev()
+            .take(var.idx())
+            .filter(|n| *n == name)
+            .count();
+        V(name.clone(), idx)
+    }
+}
+
+impl TyEnv {
+    pub fn new() -> Self {
+        TyEnv {
+            names: NameEnv::new(),
+            items: NzEnv::new(),
+        }
+    }
+    pub fn from_nzenv_alpha(items: &NzEnv) -> Self {
+        TyEnv {
+            names: NameEnv::from_binders(
+                std::iter::repeat("_".into()).take(items.size()),
+            ),
+            items: items.clone(),
+        }
+    }
+    pub fn as_varenv(&self) -> VarEnv {
+        self.names.as_varenv()
+    }
+    pub fn as_nzenv(&self) -> &NzEnv {
+        &self.items
+    }
+    pub fn as_nameenv(&self) -> &NameEnv {
+        &self.names
+    }
+
+    pub fn insert_type(&self, x: &Label, t: Type) -> Self {
+        TyEnv {
+            names: self.names.insert(x),
+            items: self.items.insert_type(t),
+        }
+    }
+    pub fn insert_value(&self, x: &Label, e: Value) -> Self {
+        TyEnv {
+            names: self.names.insert(x),
+            items: self.items.insert_value(e),
+        }
+    }
+    pub fn lookup(&self, var: &V<Label>) -> 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/mod.rs b/dhall/src/semantics/tck/mod.rs
index ba95847..28974af 100644
--- a/dhall/src/semantics/tck/mod.rs
+++ b/dhall/src/semantics/tck/mod.rs
@@ -1,4 +1,6 @@
 pub mod context;
+pub mod env;
 pub mod tyexpr;
 pub mod typecheck;
+pub(crate) use env::*;
 pub(crate) use tyexpr::*;
diff --git a/dhall/src/semantics/tck/tyexpr.rs b/dhall/src/semantics/tck/tyexpr.rs
index b64c519..262cda6 100644
--- a/dhall/src/semantics/tck/tyexpr.rs
+++ b/dhall/src/semantics/tck/tyexpr.rs
@@ -1,12 +1,10 @@
 use crate::error::{TypeError, TypeMessage};
 use crate::semantics::core::var::AlphaVar;
-use crate::semantics::nze::nzexpr::NameEnv;
-use crate::semantics::phase::normalize::{normalize_tyexpr_whnf, NzEnv};
+use crate::semantics::phase::normalize::normalize_tyexpr_whnf;
 use crate::semantics::phase::typecheck::rc;
 use crate::semantics::phase::Normalized;
 use crate::semantics::phase::{NormalizedExpr, ToExprOptions};
-use crate::semantics::tck::typecheck::TyEnv;
-use crate::semantics::Value;
+use crate::semantics::{NameEnv, NzEnv, TyEnv, Value};
 use crate::syntax::{ExprKind, Span, V};
 
 pub(crate) type Type = Value;
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index 7a225f7..789105f 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -3,71 +3,19 @@ use std::cmp::max;
 use std::collections::HashMap;
 
 use crate::error::{TypeError, TypeMessage};
-use crate::semantics::nze::{NameEnv, NzVar, VarEnv};
-use crate::semantics::phase::normalize::{merge_maps, NzEnv};
+use crate::semantics::phase::normalize::merge_maps;
 use crate::semantics::phase::typecheck::{
     builtin_to_value, const_to_value, type_of_builtin,
 };
 use crate::semantics::phase::Normalized;
 use crate::semantics::{
-    Binder, Closure, TyExpr, TyExprKind, Type, Value, ValueKind,
+    Binder, Closure, NzVar, TyEnv, TyExpr, TyExprKind, Type, Value, ValueKind,
 };
 use crate::syntax;
 use crate::syntax::{
-    BinOp, Builtin, Const, Expr, ExprKind, InterpolatedTextContents, Label,
-    Span, V,
+    BinOp, Builtin, Const, Expr, ExprKind, InterpolatedTextContents, Span,
 };
 
-#[derive(Debug, Clone)]
-pub(crate) struct TyEnv {
-    names: NameEnv,
-    items: NzEnv,
-}
-
-impl TyEnv {
-    pub fn new() -> Self {
-        TyEnv {
-            names: NameEnv::new(),
-            items: NzEnv::new(),
-        }
-    }
-    pub fn from_nzenv_alpha(items: &NzEnv) -> Self {
-        TyEnv {
-            names: NameEnv::from_binders(
-                std::iter::repeat("_".into()).take(items.size()),
-            ),
-            items: items.clone(),
-        }
-    }
-    pub fn as_varenv(&self) -> VarEnv {
-        self.names.as_varenv()
-    }
-    pub fn as_nzenv(&self) -> &NzEnv {
-        &self.items
-    }
-    pub fn as_nameenv(&self) -> &NameEnv {
-        &self.names
-    }
-
-    pub fn insert_type(&self, x: &Label, t: Type) -> Self {
-        TyEnv {
-            names: self.names.insert(x),
-            items: self.items.insert_type(t),
-        }
-    }
-    pub fn insert_value(&self, x: &Label, e: Value) -> Self {
-        TyEnv {
-            names: self.names.insert(x),
-            items: self.items.insert_value(e),
-        }
-    }
-    pub fn lookup(&self, var: &V<Label>) -> 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))
-    }
-}
-
 fn type_of_recordtype<'a>(
     tys: impl Iterator<Item = Cow<'a, TyExpr>>,
 ) -> Result<Type, TypeError> {