1 files changed, 23 insertions, 0 deletions

diff --git a/lib/prelude.ml b/lib/prelude.ml
index 57f7af3..f571a4d 100644
--- a/lib/prelude.ml
+++ b/lib/prelude.ml
@@ -16,6 +16,29 @@ module List = struct
     go
 end
 
+module Map = struct
+  include Map
+
+  let fold_result (m : ('k, 'v, _) t) ~(init : 'acc)
+      ~(f : key:'k -> data:'v -> 'acc -> ('acc, 'err) result) :
+      ('acc, 'err) result =
+    fold_until m ~init
+      ~f:(fun ~key ~data acc ->
+        match f ~key ~data acc with
+        | Ok acc' -> Continue acc'
+        | Error _ as res -> Stop res)
+      ~finish:(fun v -> Ok v)
+
+  let fold_option (m : ('k, 'v, _) t) ~(init : 'acc)
+      ~(f : key:'k -> data:'v -> 'acc -> 'acc option) : 'acc option =
+    fold_until m ~init
+      ~f:(fun ~key ~data acc ->
+        match f ~key ~data acc with
+        | Some acc' -> Continue acc'
+        | None -> Stop None)
+      ~finish:(fun v -> Some v)
+end
+
 module Z = struct
   include Z