From aabca76a62256aa7cad66c2016ed504e49651d5a Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Thu, 15 Aug 2019 13:06:56 +0200
Subject: Remove special closures from Value

Instead construct their values directly
---
 dhall/src/core/var.rs | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 35bff80..0faa091 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -67,6 +67,12 @@ impl AlphaVar {
             alpha: None,
         }
     }
+    pub fn from_var_and_alpha(normal: V<Label>, alpha: usize) -> Self {
+        AlphaVar {
+            normal,
+            alpha: Some(V((), alpha)),
+        }
+    }
 }
 
 impl AlphaLabel {
-- 
cgit v1.2.3


From a9804009f405be7e8a89e301f280ee9d51b57e5e Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Thu, 15 Aug 2019 13:08:25 +0200
Subject: Custom Debug impls to improve debug legibility

---
 dhall/src/core/var.rs | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 0faa091..d53c194 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -5,7 +5,7 @@ use dhall_syntax::{Label, V};
 /// Stores a pair of variables: a normal one and if relevant one
 /// that corresponds to the alpha-normalized version of the first one.
 /// Equality is up to alpha-equivalence.
-#[derive(Debug, Clone, Eq)]
+#[derive(Clone, Eq)]
 pub struct AlphaVar {
     normal: V<Label>,
     alpha: Option<V<()>>,
@@ -13,7 +13,7 @@ pub struct AlphaVar {
 
 // Exactly like a Label, but equality returns always true.
 // This is so that Value equality is exactly alpha-equivalence.
-#[derive(Debug, Clone, Eq)]
+#[derive(Clone, Eq)]
 pub struct AlphaLabel(Label);
 
 pub trait Shift: Sized {
@@ -125,6 +125,21 @@ impl std::cmp::PartialEq for AlphaLabel {
     }
 }
 
+impl std::fmt::Debug for AlphaVar {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self.alpha {
+            Some(a) => write!(f, "AlphaVar({}, {})", self.normal, a.1),
+            None => write!(f, "AlphaVar({}, free)", self.normal),
+        }
+    }
+}
+
+impl std::fmt::Debug for AlphaLabel {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "AlphaLabel({})", &self.0)
+    }
+}
+
 impl From<Label> for AlphaVar {
     fn from(x: Label) -> AlphaVar {
         AlphaVar {
-- 
cgit v1.2.3


From 88ebc0f9d561a2541aad84a3152511a0439db8b4 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 17:56:19 +0200
Subject: Reduce api surface of dhall crate

Helps detect unused code
---
 dhall/src/core/var.rs | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index d53c194..4ef1b93 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -16,7 +16,7 @@ pub struct AlphaVar {
 #[derive(Clone, Eq)]
 pub struct AlphaLabel(Label);
 
-pub trait Shift: Sized {
+pub(crate) trait Shift: Sized {
     // Shift an expression to move it around binders without changing the meaning of its free
     // variables. Shift by 1 to move an expression under a binder. Shift by -1 to extract an
     // expression from under a binder, if the expression does not refer to that bound variable.
@@ -50,24 +50,24 @@ pub trait Shift: Sized {
     }
 }
 
-pub trait Subst<T> {
+pub(crate) trait Subst<T> {
     fn subst_shift(&self, var: &AlphaVar, val: &T) -> Self;
 }
 
 impl AlphaVar {
-    pub fn to_var(&self, alpha: bool) -> V<Label> {
+    pub(crate) fn to_var(&self, alpha: bool) -> V<Label> {
         match (alpha, &self.alpha) {
             (true, Some(x)) => V("_".into(), x.1),
             _ => self.normal.clone(),
         }
     }
-    pub fn from_var(normal: V<Label>) -> Self {
+    pub(crate) fn from_var(normal: V<Label>) -> Self {
         AlphaVar {
             normal,
             alpha: None,
         }
     }
-    pub fn from_var_and_alpha(normal: V<Label>, alpha: usize) -> Self {
+    pub(crate) fn from_var_and_alpha(normal: V<Label>, alpha: usize) -> Self {
         AlphaVar {
             normal,
             alpha: Some(V((), alpha)),
@@ -76,14 +76,14 @@ impl AlphaVar {
 }
 
 impl AlphaLabel {
-    pub fn to_label_maybe_alpha(&self, alpha: bool) -> Label {
+    pub(crate) fn to_label_maybe_alpha(&self, alpha: bool) -> Label {
         if alpha {
             "_".into()
         } else {
             self.to_label()
         }
     }
-    pub fn to_label(&self) -> Label {
+    pub(crate) fn to_label(&self) -> Label {
         self.clone().into()
     }
 }
-- 
cgit v1.2.3


From 5f0d69671b44ba1dff6becb9ebc7f6e74241e3e2 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 18:14:55 +0200
Subject: Remove dead code

---
 dhall/src/core/var.rs | 6 ------
 1 file changed, 6 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 4ef1b93..5e7bf05 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -61,12 +61,6 @@ impl AlphaVar {
             _ => self.normal.clone(),
         }
     }
-    pub(crate) fn from_var(normal: V<Label>) -> Self {
-        AlphaVar {
-            normal,
-            alpha: None,
-        }
-    }
     pub(crate) fn from_var_and_alpha(normal: V<Label>, alpha: usize) -> Self {
         AlphaVar {
             normal,
-- 
cgit v1.2.3


From 9babfb33ab95a93d1e2b70c54ee8100409253ce9 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 18:40:36 +0200
Subject: Free variables don't exist anymore

---
 dhall/src/core/var.rs | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 5e7bf05..becd653 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -2,13 +2,13 @@ use std::collections::HashMap;
 
 use dhall_syntax::{Label, V};
 
-/// Stores a pair of variables: a normal one and if relevant one
+/// Stores a pair of variables: a normal one and one
 /// that corresponds to the alpha-normalized version of the first one.
-/// Equality is up to alpha-equivalence.
+/// Equality is up to alpha-equivalence (compares on the second one only).
 #[derive(Clone, Eq)]
 pub struct AlphaVar {
     normal: V<Label>,
-    alpha: Option<V<()>>,
+    alpha: V<()>,
 }
 
 // Exactly like a Label, but equality returns always true.
@@ -56,15 +56,16 @@ pub(crate) trait Subst<T> {
 
 impl AlphaVar {
     pub(crate) fn to_var(&self, alpha: bool) -> V<Label> {
-        match (alpha, &self.alpha) {
-            (true, Some(x)) => V("_".into(), x.1),
-            _ => self.normal.clone(),
+        if alpha {
+            V("_".into(), self.alpha.1)
+        } else {
+            self.normal.clone()
         }
     }
     pub(crate) fn from_var_and_alpha(normal: V<Label>, alpha: usize) -> Self {
         AlphaVar {
             normal,
-            alpha: Some(V((), alpha)),
+            alpha: V((), alpha),
         }
     }
 }
@@ -86,10 +87,7 @@ impl Shift for AlphaVar {
     fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
         Some(AlphaVar {
             normal: self.normal.shift(delta, &var.normal)?,
-            alpha: match (&self.alpha, &var.alpha) {
-                (Some(x), Some(v)) => Some(x.shift(delta, v)?),
-                _ => None,
-            },
+            alpha: self.alpha.shift(delta, &var.alpha)?,
         })
     }
 }
@@ -104,13 +102,10 @@ impl<T> Subst<T> for () {
     fn subst_shift(&self, _var: &AlphaVar, _val: &T) -> Self {}
 }
 
+/// Equality up to alpha-equivalence
 impl std::cmp::PartialEq for AlphaVar {
     fn eq(&self, other: &Self) -> bool {
-        match (&self.alpha, &other.alpha) {
-            (Some(x), Some(y)) => x == y,
-            (None, None) => self.normal == other.normal,
-            _ => false,
-        }
+        self.alpha == other.alpha
     }
 }
 impl std::cmp::PartialEq for AlphaLabel {
@@ -121,10 +116,7 @@ impl std::cmp::PartialEq for AlphaLabel {
 
 impl std::fmt::Debug for AlphaVar {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match &self.alpha {
-            Some(a) => write!(f, "AlphaVar({}, {})", self.normal, a.1),
-            None => write!(f, "AlphaVar({}, free)", self.normal),
-        }
+        write!(f, "AlphaVar({}, {})", self.normal, self.alpha.1)
     }
 }
 
@@ -138,7 +130,7 @@ impl From<Label> for AlphaVar {
     fn from(x: Label) -> AlphaVar {
         AlphaVar {
             normal: V(x, 0),
-            alpha: Some(V((), 0)),
+            alpha: V((), 0),
         }
     }
 }
-- 
cgit v1.2.3


From e0f5216215ccb7a4df85d80e11dd265cdb52a44f Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 19:47:36 +0200
Subject: s/Value/ValueF/

---
 dhall/src/core/var.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index becd653..296e968 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -12,7 +12,7 @@ pub struct AlphaVar {
 }
 
 // Exactly like a Label, but equality returns always true.
-// This is so that Value equality is exactly alpha-equivalence.
+// This is so that ValueF equality is exactly alpha-equivalence.
 #[derive(Clone, Eq)]
 pub struct AlphaLabel(Label);
 
-- 
cgit v1.2.3


From 961dbc0e9d52691de590568c01a22d28c04fe2f5 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 21:59:11 +0200
Subject: Store type in Thunk

---
 dhall/src/core/var.rs | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 296e968..3af12ec 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -50,8 +50,8 @@ pub(crate) trait Shift: Sized {
     }
 }
 
-pub(crate) trait Subst<T> {
-    fn subst_shift(&self, var: &AlphaVar, val: &T) -> Self;
+pub(crate) trait Subst<S> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self;
 }
 
 impl AlphaVar {
@@ -98,8 +98,35 @@ impl Shift for () {
     }
 }
 
-impl<T> Subst<T> for () {
-    fn subst_shift(&self, _var: &AlphaVar, _val: &T) -> Self {}
+impl<T: Shift> Shift for Option<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(match self {
+            None => None,
+            Some(x) => Some(x.shift(delta, var)?),
+        })
+    }
+}
+
+impl<T: Shift> Shift for Box<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(Box::new(self.as_ref().shift(delta, var)?))
+    }
+}
+
+impl<S> Subst<S> for () {
+    fn subst_shift(&self, _var: &AlphaVar, _val: &S) -> Self {}
+}
+
+impl<S, T: Subst<S>> Subst<S> for Option<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        self.as_ref().map(|x| x.subst_shift(var, val))
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for Box<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        Box::new(self.as_ref().subst_shift(var, val))
+    }
 }
 
 /// Equality up to alpha-equivalence
-- 
cgit v1.2.3


From cc0c6cc420ca8019665e745797758c997cc35358 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 22:33:16 +0200
Subject: Use generic Shift/Subst impls

---
 dhall/src/core/var.rs | 175 +++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 138 insertions(+), 37 deletions(-)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 3af12ec..8d02171 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -92,43 +92,6 @@ impl Shift for AlphaVar {
     }
 }
 
-impl Shift for () {
-    fn shift(&self, _delta: isize, _var: &AlphaVar) -> Option<Self> {
-        Some(())
-    }
-}
-
-impl<T: Shift> Shift for Option<T> {
-    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
-        Some(match self {
-            None => None,
-            Some(x) => Some(x.shift(delta, var)?),
-        })
-    }
-}
-
-impl<T: Shift> Shift for Box<T> {
-    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
-        Some(Box::new(self.as_ref().shift(delta, var)?))
-    }
-}
-
-impl<S> Subst<S> for () {
-    fn subst_shift(&self, _var: &AlphaVar, _val: &S) -> Self {}
-}
-
-impl<S, T: Subst<S>> Subst<S> for Option<T> {
-    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
-        self.as_ref().map(|x| x.subst_shift(var, val))
-    }
-}
-
-impl<S, T: Subst<S>> Subst<S> for Box<T> {
-    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
-        Box::new(self.as_ref().subst_shift(var, val))
-    }
-}
-
 /// Equality up to alpha-equivalence
 impl std::cmp::PartialEq for AlphaVar {
     fn eq(&self, other: &Self) -> bool {
@@ -188,3 +151,141 @@ impl From<AlphaLabel> for Label {
         x.0
     }
 }
+impl Shift for () {
+    fn shift(&self, _delta: isize, _var: &AlphaVar) -> Option<Self> {
+        Some(())
+    }
+}
+
+impl<T: Shift> Shift for Option<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(match self {
+            None => None,
+            Some(x) => Some(x.shift(delta, var)?),
+        })
+    }
+}
+
+impl<T: Shift> Shift for Box<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(Box::new(self.as_ref().shift(delta, var)?))
+    }
+}
+
+impl<T: Shift> Shift for std::rc::Rc<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(std::rc::Rc::new(self.as_ref().shift(delta, var)?))
+    }
+}
+
+impl<T: Shift> Shift for std::cell::RefCell<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(std::cell::RefCell::new(self.borrow().shift(delta, var)?))
+    }
+}
+
+impl<T: Shift, E: Clone> Shift for dhall_syntax::ExprF<T, E> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(self.traverse_ref_with_special_handling_of_binders(
+            |v| Ok(v.shift(delta, var)?),
+            |x, v| Ok(v.shift(delta, &var.under_binder(x))?),
+        )?)
+    }
+}
+
+impl<T: Shift> Shift for Vec<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(
+            self.iter()
+                .map(|v| Ok(v.shift(delta, var)?))
+                .collect::<Result<_, _>>()?,
+        )
+    }
+}
+
+impl<K, T: Shift> Shift for HashMap<K, T>
+where
+    K: Clone + std::hash::Hash + Eq,
+{
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some(
+            self.iter()
+                .map(|(k, v)| Ok((k.clone(), v.shift(delta, var)?)))
+                .collect::<Result<_, _>>()?,
+        )
+    }
+}
+
+impl<T: Shift> Shift for dhall_syntax::InterpolatedTextContents<T> {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        use dhall_syntax::InterpolatedTextContents::{Expr, Text};
+        Some(match self {
+            Expr(x) => Expr(x.shift(delta, var)?),
+            Text(s) => Text(s.clone()),
+        })
+    }
+}
+
+impl<S> Subst<S> for () {
+    fn subst_shift(&self, _var: &AlphaVar, _val: &S) -> Self {}
+}
+
+impl<S, T: Subst<S>> Subst<S> for Option<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        self.as_ref().map(|x| x.subst_shift(var, val))
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for Box<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        Box::new(self.as_ref().subst_shift(var, val))
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for std::rc::Rc<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        std::rc::Rc::new(self.as_ref().subst_shift(var, val))
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for std::cell::RefCell<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        std::cell::RefCell::new(self.borrow().subst_shift(var, val))
+    }
+}
+
+impl<S: Shift, T: Subst<S>, E: Clone> Subst<S> for dhall_syntax::ExprF<T, E> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        self.map_ref_with_special_handling_of_binders(
+            |v| v.subst_shift(var, val),
+            |x, v| v.subst_shift(&var.under_binder(x), &val.under_binder(x)),
+        )
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for Vec<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        self.iter().map(|v| v.subst_shift(var, val)).collect()
+    }
+}
+
+impl<S, T: Subst<S>> Subst<S> for dhall_syntax::InterpolatedTextContents<T> {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        use dhall_syntax::InterpolatedTextContents::{Expr, Text};
+        match self {
+            Expr(x) => Expr(x.subst_shift(var, val)),
+            Text(s) => Text(s.clone()),
+        }
+    }
+}
+
+impl<S, K, T: Subst<S>> Subst<S> for HashMap<K, T>
+where
+    K: Clone + std::hash::Hash + Eq,
+{
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        self.iter()
+            .map(|(k, v)| (k.clone(), v.subst_shift(var, val)))
+            .collect()
+    }
+}
-- 
cgit v1.2.3


From 8dec798929f35df15a7bc3a6caa4f0c7954c4ffc Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 16 Aug 2019 23:17:46 +0200
Subject: Share type alongside the value in a thunk

---
 dhall/src/core/var.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'dhall/src/core/var.rs')

diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 8d02171..ce4d137 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -157,6 +157,12 @@ impl Shift for () {
     }
 }
 
+impl<A: Shift, B: Shift> Shift for (A, B) {
+    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+        Some((self.0.shift(delta, var)?, self.1.shift(delta, var)?))
+    }
+}
+
 impl<T: Shift> Shift for Option<T> {
     fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
         Some(match self {
@@ -230,6 +236,12 @@ impl<S> Subst<S> for () {
     fn subst_shift(&self, _var: &AlphaVar, _val: &S) -> Self {}
 }
 
+impl<S, A: Subst<S>, B: Subst<S>> Subst<S> for (A, B) {
+    fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+        (self.0.subst_shift(var, val), self.1.subst_shift(var, val))
+    }
+}
+
 impl<S, T: Subst<S>> Subst<S> for Option<T> {
     fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
         self.as_ref().map(|x| x.subst_shift(var, val))
-- 
cgit v1.2.3