Make App() only store one argument

4 files changed, 7 insertions, 16 deletions

diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index 56ab66c..ab29148 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -150,7 +150,7 @@ pub enum ExprF<SubExpr, Label, Note, Embed> {
     ///  `∀(x : A) -> B`
     Pi(Label, SubExpr, SubExpr),
     ///  `f a`
-    App(SubExpr, Vec<SubExpr>),
+    App(SubExpr, SubExpr),
     ///  `let x     = r in e`
     ///  `let x : t = r in e`
     Let(Label, Option<SubExpr>, SubExpr, SubExpr),
diff --git a/dhall_core/src/parser.rs b/dhall_core/src/parser.rs
index 2a30b2b..051a4e6 100644
--- a/dhall_core/src/parser.rs
+++ b/dhall_core/src/parser.rs
@@ -743,10 +743,10 @@ make_parser! {
 
     token_rule!(Some_<()>);
 
-    rule!(application_expression<ParsedExpr<'a>> as expression; span; children!(
+    rule!(application_expression<ParsedExpr<'a>> as expression; children!(
         [expression(e)] => e,
         [expression(first), expression(rest)..] => {
-            spanned(span, App(rc(first), rest.map(rc).collect()))
+            rest.fold(first, |acc, e| App(rc(acc), rc(e)))
         },
     ));
 
diff --git a/dhall_core/src/printer.rs b/dhall_core/src/printer.rs
index 4d1ae2d..85105d9 100644
--- a/dhall_core/src/printer.rs
+++ b/dhall_core/src/printer.rs
@@ -56,12 +56,8 @@ impl<SE: Display + Clone, N, E: Display> Display for ExprF<SE, Label, N, E> {
             ExprF::BinOp(op, a, b) => {
                 write!(f, "{} {} {}", a, op, b)?;
             }
-            ExprF::App(a, args) => {
-                a.fmt(f)?;
-                for x in args {
-                    f.write_str(" ")?;
-                    x.fmt(f)?;
-                }
+            ExprF::App(a, b) => {
+                write!(f, "{} {}", a, b)?;
             }
             Field(a, b) => {
                 write!(f, "{}.{}", a, b)?;
@@ -216,10 +212,7 @@ impl<S: Clone, A: Display + Clone> Expr<S, A> {
             OldOptionalLit(x, t) => OldOptionalLit(x, t.phase(Import)),
             EmptyOptionalLit(t) => EmptyOptionalLit(t.phase(Import)),
             NEOptionalLit(e) => NEOptionalLit(e.phase(Import)),
-            ExprF::App(a, args) => ExprF::App(
-                a.phase(Import),
-                args.into_iter().map(|x| x.phase(Import)).collect(),
-            ),
+            ExprF::App(f, a) => ExprF::App(f.phase(Import), a.phase(Import)),
             Field(a, b) => Field(a.phase(Primitive), b),
             Projection(e, ls) => Projection(e.phase(Primitive), ls),
             Note(n, b) => Note(n, b.phase(phase)),
diff --git a/dhall_core/src/visitor.rs b/dhall_core/src/visitor.rs
index 16ad418..9111414 100644
--- a/dhall_core/src/visitor.rs
+++ b/dhall_core/src/visitor.rs
@@ -130,9 +130,7 @@ where
                 let (l, e) = v.visit_binder(l, e)?;
                 Let(l, t, a, e)
             }
-            App(f, args) => {
-                App(v.visit_subexpr(f)?, vec(args, |e| v.visit_subexpr(e))?)
-            }
+            App(f, a) => App(v.visit_subexpr(f)?, v.visit_subexpr(a)?),
             Annot(x, t) => Annot(v.visit_subexpr(x)?, v.visit_subexpr(t)?),
             Const(k) => Const(*k),
             Builtin(v) => Builtin(*v),