Evaluate both side of application

1 files changed, 8 insertions, 1 deletions

diff --git a/rust/src/lambda.rs b/rust/src/lambda.rs
index 0080f63..b05bd22 100644
--- a/rust/src/lambda.rs
+++ b/rust/src/lambda.rs
@@ -17,7 +17,7 @@ pub fn run(arg: &str) -> String {
 
 fn interpret(arg: &Value) -> Value {
     match arg {
-        Value::App(l, r) => apply(&interpret(l), r),
+        Value::App(l, r) => apply(&interpret(l), &interpret(r)),
         other => other.clone(),
     }
 }
@@ -87,4 +87,11 @@ mod lambda_test {
         let value = parse("(((lam x (lam x x)) 13) 12)");
         assert_eq!(Value::Num(12), interpret(&value));
     }
+
+    #[test]
+    fn interpretation_applies_to_both_sides_of_application() {
+        let value = parse("((lam x x) ((lam x x) 12))");
+        assert_eq!(Value::Num(12), interpret(&value));
+    }
+
 }