From a2210f2db3013fc7f5bcad5afa1792e994dcd414 Mon Sep 17 00:00:00 2001
From: Roman Godmaire <godmaire@twilit.io>
Date: Tue, 14 May 2024 14:48:52 -0400
Subject: [PATCH] fix: 1-based indexing, babey

---
 mute-interpreter/src/env/core.rs  | 6 +++++-
 mute-interpreter/src/evaluator.rs | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/mute-interpreter/src/env/core.rs b/mute-interpreter/src/env/core.rs
index 6c75124..40333d8 100644
--- a/mute-interpreter/src/env/core.rs
+++ b/mute-interpreter/src/env/core.rs
@@ -334,7 +334,11 @@ pub(super) fn core() -> HashMap<String, Value> {
                     }
                 };
 
-                list.get(nth).unwrap().clone()
+                if nth < 1 {
+                    return Node::Error(format!("TypeError: expected positive int, got {}", nth));
+                }
+
+                list.get(nth - 1).unwrap().clone()
             }),
         ),
         (
diff --git a/mute-interpreter/src/evaluator.rs b/mute-interpreter/src/evaluator.rs
index 5ebb6f5..3a79597 100644
--- a/mute-interpreter/src/evaluator.rs
+++ b/mute-interpreter/src/evaluator.rs
@@ -474,7 +474,7 @@ mod test {
     // List Manipulation
     #[case("(first (list 1 2 3))", "1")]
     #[case("(last (list 1 2 3))", "3")]
-    #[case("(nth (list 1 2 3) 1)", "2")]
+    #[case("(nth (list 1 2 3) 2)", "2")]
     #[case("(push-front (list 1 2 3) 0)", "(0 1 2 3)")]
     #[case("(push-back (list 1 2 3) 4)", "(1 2 3 4)")]
     #[case("(pop-front (list 1 2 3))", "(2 3)")]