Add split_result (#459)

add `CCList.split_result` (@seprov)

src/core/CCList.ml

@@ -1048,6 +1048,13 @@ let all_ok l =
     | None -> assert false
     | Some e -> Error e)
 
+let split_result results =
+  results
+  |> partition_filter_map (fun x ->
+         match x with 
+         | Ok o -> `Left o 
+         | Error e -> `Right e)
+
 let group_by (type k) ?(hash = Hashtbl.hash) ?(eq = Stdlib.( = )) l =
   let module Tbl = Hashtbl.Make (struct
     type t = k

src/core/CCList.mli

@@ -495,6 +495,10 @@ val all_ok : ('a, 'err) result t -> ('a t, 'err) result
     @since 1.3, but only
     @since 2.2 with labels *)
 
+val split_result : ('ok, 'error) result list -> 'ok list * 'error list
+(** Split a list of results into [Ok]s and [Error]s.
+    @since NEXT_RELEASE *)
+    
 val sorted_mem : cmp:('a -> 'a -> int) -> 'a -> 'a list -> bool
 (** [sorted_mem ~cmp x l] and [mem x l] give the same result for any sorted list [l],
     but potentially more efficiently.