fix: removed unneccessary lowering from SCons(x, Nil) to x when getting matched arms

1 files changed, 3 insertions, 6 deletions

diff --git a/src/sexp/step.rs b/src/sexp/step.rs
index 3168c5b..1a336e3 100644
--- a/src/sexp/step.rs
+++ b/src/sexp/step.rs
@@ -296,7 +296,7 @@ impl SExp {
     /// let expshould = parse_to_ast("case 3 (3 true) (_ false)");
     /// assert_eq!(exp, expshould);
     /// let exp = exp.and_then(|e| e.step());
-    /// assert_eq!(exp, Ok(Atom(True)));
+    /// assert_eq!(exp, Ok(scons(Atom(True), Nil)));
     ///
     /// let exp = "case (coprod Bool (+ 1 2)) ((inl b) (if b 1 0)) ((inr x) (- x 1))";
     /// let exp = parse_to_ast(exp);
@@ -304,7 +304,7 @@ impl SExp {
     /// let expshould = parse_to_ast("case (coprod Bool 3) ((inl b) (if b 1 0)) ((inr x) (- x 1))");
     /// assert_eq!(exp, expshould);
     /// let exp = exp.and_then(|e| e.step());
-    /// assert_eq!(exp, Ok(scons(Sub, scons(3, scons(1, Nil)))));
+    /// assert_eq!(exp, parse_to_ast("(- 3 1)"));
     /// ```
     ///
     /// Shadowing:
@@ -371,10 +371,7 @@ impl SExp {
 			SCons(pat, arm) => Ok((*pat, *arm)),
 			_ => Err("unreachable after type checking".to_string())
 		    }?;
-		    let mut arm = match arm {
-			SCons(x, n) if *n == Atom(Nil) => *x,
-			t => t,
-		    };
+                    let mut arm = arm;
 
 		    if let Some(ctx) = scrutinee.matches_pat(&pat) {
 			for (name, value) in ctx {