optimize map:fold recursion

2 files changed, 16 insertions, 9 deletions

diff --git a/gen/src/map_dict.erl b/gen/src/map_dict.erl
index e72b92d..5155ec7 100644
--- a/gen/src/map_dict.erl
+++ b/gen/src/map_dict.erl
@@ -75,12 +75,15 @@ update(Dict, Key, F) ->
             put(Dict, Key, F({error, not_found}))
     end.
 
-fold(Dict, Acc, F) ->
-    Kvs = to_list(Dict),
-    case Kvs of
+do_fold(List, Acc, F) ->
+    case List of
         [] ->
             Acc;
 
-        [{K, V} | _] ->
-            fold(delete(Dict, K), F(K, V, Acc), F)
+        [{K, V} | Tail] ->
+            do_fold(Tail, F(K, V, Acc), F)
     end.
+
+fold(Dict, Acc, F) ->
+    Kvs = to_list(Dict),
+    do_fold(Kvs, Acc, F).
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)
+}