optimize map:fold recursion

1 files changed, 8 insertions, 4 deletions

diff --git a/src/map_dict.gleam b/src/map_dict.gleam
index c25378f..2ec141a 100644
--- a/src/map_dict.gleam
+++ b/src/map_dict.gleam
@@ -87,10 +87,14 @@ pub fn update(dict, key, f) {
   }
 }
 
-pub fn fold(dict, acc, f) {
-  let kvs = to_list(dict)
-  case kvs {
+fn do_fold(list, acc, f) {
+  case list {
     | [] -> acc
-    | [{k, v} | _] -> fold(delete(dict, k), f(k, v, acc), f)
+    | [{k, v} | tail] -> do_fold(tail, f(k, v, acc), f)
   }
 }
+
+pub fn fold(dict, acc, f) {
+  let kvs = to_list(dict)
+  do_fold(kvs, acc, f)
+}