Add utility functions to result

all and concat_map

src/stdune/result.ml

@@ -29,3 +29,25 @@ module O = struct
   let ( >>= ) t f = bind t ~f
   let ( >>| ) t f = map  t ~f
 end
+
+open O
+
+let all =
+  let rec loop acc = function
+    | [] -> Ok (List.rev acc)
+    | t :: l ->
+      t >>= fun x ->
+      loop (x :: acc) l
+  in
+  fun l -> loop [] l
+
+let concat_map =
+  let rec loop f acc = function
+    | [] -> Ok (List.rev acc)
+    | x :: l ->
+      f x >>= fun y ->
+      loop f (List.rev_append y acc) l
+  in
+  fun l ~f -> loop f [] l
+
+type ('a, 'error) result = ('a, 'error) t

src/stdune/result.mli

@@ -16,3 +16,13 @@ val map  : ('a, 'error) t -> f:('a -> 'b) -> ('b, 'error) t
 val bind : ('a, 'error) t -> f:('a -> ('b, 'error) t) -> ('b, 'error) t
 
 val map_error : ('a, 'error1) t -> f:('error1 -> 'error2) -> ('a, 'error2) t
+
+val all : ('a, 'error) t list -> ('a list, 'error) t
+
+val concat_map
+  :  'a list
+  -> f:('a -> ('b list, 'error) t)
+  -> ('b list, 'error) t
+
+(** For compatibility with some other code *)
+type ('a, 'error) result = ('a, 'error) t