Initial commit

lib/result_augmented.ml

@@ -0,0 +1,42 @@
+module Internal_result = struct
+  type ('a, 'b) t = ('a, 'b) result = Ok of 'a | Error of 'b
+
+  let return x = Ok x
+  let error e = Error e
+  let error_string s = Error (`Error_message s)
+  let bind = Stdlib.Result.bind
+  let ok = Result.ok
+
+  module List = struct
+    let map (xs : 'a list) ~(f : 'a -> ('b, 'c) t) : ('b list, 'c) t =
+      let rec loop ?(acc = []) xs =
+        match xs with
+        | [] -> return (List.rev acc)
+        | hd :: tl -> (
+            match f hd with
+            | Ok x -> loop ~acc:(x :: acc) tl
+            | Error e -> Error e)
+      in
+      loop xs
+
+    let iteri ?(start = 0) (xs : 'a list) ~(f : int -> 'a -> (unit, 'b) t) : (unit, 'b) t =
+      let rec loop ?(idx = start) xs =
+        match xs with
+        | [] -> return ()
+        | hd :: tl -> begin
+            let res = f idx hd in
+            match res with
+            | Ok () -> loop ~idx:(idx + 1) tl
+            | Error e -> Error e
+          end
+      in
+      loop xs
+  end
+
+  module Let_syntax = struct
+    let ( let* ) = Stdlib.Result.bind
+    let ( let+ ) x f = Stdlib.Result.map f x
+  end
+end
+
+include Internal_result