Reduce duplication between mapping functions

3 files changed, 35 insertions, 60 deletions

diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index d0e908b..7f9fd14 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -273,9 +273,21 @@ impl<SE, L, N, E> ExprF<SE, L, N, E> {
         })
     }
 
-    pub fn map_ref<'a, SE2, L2, N2, E2, F1, F3, F4, F5>(
+    pub fn map_ref_with_special_handling_of_binders<
+        'a,
+        SE2,
+        L2,
+        N2,
+        E2,
+        F1,
+        F2,
+        F3,
+        F4,
+        F5,
+    >(
         &'a self,
         mut map_subexpr: F1,
+        mut map_under_binder: F2,
         map_note: F3,
         map_embed: F4,
         mut map_label: F5,
@@ -284,33 +296,23 @@ impl<SE, L, N, E> ExprF<SE, L, N, E> {
         L: Ord,
         L2: Ord,
         F1: FnMut(&'a SE) -> SE2,
+        F2: FnMut(&'a L, &'a SE) -> SE2,
         F3: FnOnce(&'a N) -> N2,
         F4: FnOnce(&'a E) -> E2,
         F5: FnMut(&'a L) -> L2,
     {
-        trivial_result(self.traverse_ref(
+        trivial_result(self.traverse_ref_with_special_handling_of_binders(
             |x| Ok(map_subexpr(x)),
+            |l, x| Ok(map_under_binder(l, x)),
             |x| Ok(map_note(x)),
             |x| Ok(map_embed(x)),
             |x| Ok(map_label(x)),
         ))
     }
 
-    pub fn map_ref_with_special_handling_of_binders<
-        'a,
-        SE2,
-        L2,
-        N2,
-        E2,
-        F1,
-        F2,
-        F3,
-        F4,
-        F5,
-    >(
+    pub fn map_ref<'a, SE2, L2, N2, E2, F1, F3, F4, F5>(
         &'a self,
         mut map_subexpr: F1,
-        mut map_under_binder: F2,
         map_note: F3,
         map_embed: F4,
         mut map_label: F5,
@@ -319,14 +321,12 @@ impl<SE, L, N, E> ExprF<SE, L, N, E> {
         L: Ord,
         L2: Ord,
         F1: FnMut(&'a SE) -> SE2,
-        F2: FnMut(&'a L, &'a SE) -> SE2,
         F3: FnOnce(&'a N) -> N2,
         F4: FnOnce(&'a E) -> E2,
         F5: FnMut(&'a L) -> L2,
     {
-        trivial_result(self.traverse_ref_with_special_handling_of_binders(
+        trivial_result(self.traverse_ref(
             |x| Ok(map_subexpr(x)),
-            |l, x| Ok(map_under_binder(l, x)),
             |x| Ok(map_note(x)),
             |x| Ok(map_embed(x)),
             |x| Ok(map_label(x)),
@@ -362,51 +362,24 @@ impl<SE, L, N, E> ExprF<SE, L, N, E> {
 }
 
 impl<N, E> Expr<N, E> {
-    pub fn map_shallow<N2, E2, F1, F2, F3, F4>(
+    pub fn traverse_embed<E2, Err, F>(
         &self,
-        map_expr: F1,
-        map_note: F2,
-        map_embed: F3,
-        map_label: F4,
-    ) -> Expr<N2, E2>
+        map_embed: F,
+    ) -> Result<Expr<N, E2>, Err>
     where
-        E: Clone,
-        N2: Clone,
         N: Clone,
-        F1: Fn(&Self) -> Expr<N2, E2>,
-        F2: Fn(&N) -> N2,
-        F3: Fn(&E) -> E2,
-        F4: Fn(&Label) -> Label,
+        F: FnMut(&E) -> Result<E2, Err>,
     {
-        self.map_ref(
-            |x| rc(map_expr(x.as_ref())),
-            map_note,
-            map_embed,
-            map_label,
-        )
+        self.visit(&mut visitor::TraverseEmbedVisitor(map_embed))
     }
 
-    pub fn map_embed<E2, F>(&self, map_embed: &F) -> Expr<N, E2>
+    pub fn map_embed<E2, F>(&self, mut map_embed: F) -> Expr<N, E2>
     where
         E: Clone,
         N: Clone,
-        F: Fn(&E) -> E2,
+        F: FnMut(&E) -> E2,
     {
-        let recurse =
-            |e: &Expr<N, E>| -> Expr<N, E2> { e.map_embed(map_embed) };
-        self.map_shallow(recurse, N::clone, map_embed, Label::clone)
-    }
-
-    pub fn traverse_embed<E2, Err, F>(
-        &self,
-        map_embed: F,
-    ) -> Result<Expr<N, E2>, Err>
-    where
-        N: Clone,
-        E2: Clone,
-        F: FnMut(&E) -> Result<E2, Err>,
-    {
-        self.visit(&mut visitor::TraverseEmbedVisitor(map_embed))
+        trivial_result(self.traverse_embed(|x| Ok(map_embed(x))))
     }
 
     pub fn map_label<F>(&self, map_label: &F) -> Self
@@ -415,8 +388,10 @@ impl<N, E> Expr<N, E> {
         N: Clone,
         F: Fn(&Label) -> Label,
     {
-        let recurse = |e: &Self| -> Self { e.map_label(map_label) };
-        self.map_shallow(recurse, N::clone, E::clone, map_label)
+        let recurse = |e: &SubExpr<N, E>| -> SubExpr<N, E> {
+            rc(e.as_ref().map_label(map_label))
+        };
+        self.map_ref(recurse, N::clone, E::clone, map_label)
     }
 
     pub fn roll(&self) -> SubExpr<N, E>
@@ -447,11 +422,12 @@ impl<E: Clone> Expr<X, E> {
 
 impl<N: Clone> Expr<N, X> {
     // Deprecated, use embed_absurd instead
-    pub fn absurd_rec<T>(&self) -> Expr<N, T> {
+    pub fn absurd_rec<E>(&self) -> Expr<N, E> {
         self.embed_absurd()
     }
-    pub fn embed_absurd<T>(&self) -> Expr<N, T> {
+    pub fn embed_absurd<E>(&self) -> Expr<N, E> {
         self.visit(&mut visitor::EmbedAbsurdVisitor)
+        // self.visit(&mut visitor::SquashEmbedVisitor(|e| match *e {}))
     }
 }
 
diff --git a/dhall_core/src/visitor.rs b/dhall_core/src/visitor.rs
index c6b7321..053932d 100644
--- a/dhall_core/src/visitor.rs
+++ b/dhall_core/src/visitor.rs
@@ -433,7 +433,6 @@ impl<'a, 'b, N, E, E2, Err, F1>
     > for &'b mut TraverseEmbedVisitor<F1>
 where
     N: Clone + 'a,
-    E2: Clone,
     F1: FnMut(&E) -> Result<E2, Err>,
 {
     type Error = Err;
diff --git a/dhall_generator/src/quote.rs b/dhall_generator/src/quote.rs
index 7128511..d680288 100644
--- a/dhall_generator/src/quote.rs
+++ b/dhall_generator/src/quote.rs
@@ -10,7 +10,7 @@ pub fn expr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let expr: SubExpr<_, Import> = parse_expr(&input_str).unwrap().unnote();
     let no_import =
         |_: &Import| -> X { panic!("Don't use import in dhall::expr!()") };
-    let expr = expr.as_ref().map_embed(&no_import);
+    let expr = expr.as_ref().map_embed(no_import);
     let output = quote_expr(&expr, &Context::new());
     output.into()
 }
@@ -20,7 +20,7 @@ pub fn subexpr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let expr: SubExpr<_, Import> = parse_expr(&input_str).unwrap().unnote();
     let no_import =
         |_: &Import| -> X { panic!("Don't use import in dhall::subexpr!()") };
-    let expr = expr.as_ref().map_embed(&no_import);
+    let expr = expr.as_ref().map_embed(no_import);
     let output = quote_subexpr(&dhall_core::rc(expr), &Context::new());
     output.into()
 }