Reduce Boxing for Apply

src/expr.rs

@@ -13,7 +13,7 @@ pub enum Expr {
 
     // Functions
     Func(String, Box<Expr>),
-    Apply(Box<Expr>, Box<Expr>),
+    Apply(Box<(Expr, Expr)>),
     Operator(Box<Expr>, Operator, Box<Expr>),
     Closure(Vec<Pattern>, Box<Expr>),
 

src/parse.rs

@@ -190,7 +190,7 @@ where I: Stream<Item = char, Position = IndentablePosition>,
         match opt_expr2 {
             None => expr1,
             Some(expr2) => {
-                Expr::Apply(Box::new(expr1), Box::new(expr2))
+                Expr::Apply(Box::new((expr1, expr2)))
             },
         }
     )

tests/test_parse.rs

@@ -363,7 +363,7 @@ mod tests {
 
     fn expect_parsed_apply<'a>(parse_str: &'a str, expr1: Expr, expr2: Expr) {
         assert_eq!(
-            Ok((Apply(Box::new(expr1), Box::new(expr2)), "")),
+            Ok((Apply(Box::new((expr1, expr2))), "")),
             parse_standalone(parse_str)
         );
     }