Move to result

Author: mchaver

jscomp/others/belt.ml

@@ -232,9 +232,9 @@ module HashSet = Belt_HashSet
 *)
 module HashMap = Belt_HashMap
 
-(** {!Belt.Either}
+(** {!Belt.Result}
     
     The top level provides generic {b immutable} either operations.
 *)
 
-module Either = Belt_Either               
+module Result = Belt_Result

jscomp/others/belt_Either.ml

@@ -0,0 +1,63 @@
+(* https://gist.github.com/NicolasT/65dad40b203da7c65b4c *)
+
+type ('a, 'b) t =
+  | Ok of 'a
+  | Error of 'b
+                                      
+(** Constructor functions *)
+let ok a = Ok a
+let error b = error b
+
+let result a b = function
+  | Ok v -> a v
+  | Error v -> b v
+
+(** Bifunctor interface *)
+let bimap a b = result (fun v -> ok (a v)) (fun v -> error (b v))
+
+external id : 'a -> 'a = "%identity"
+let const v = fun _ -> v
+
+(** Functor interface *)
+let map f = bimap id f
+let (<$>) = map
+let mapLeft f = bimap f id
+
+(** Predicates *)
+let isOk v = result (const true) (const false) v
+let isError v = result (const false) (const true) v
+
+let toString a b = result
+                     (fun v -> "Ok (" ^ (a v) ^ ")")
+                     (fun v -> "Error (" ^ (b v) ^ ")")
+
+let fold f z = result (const z) (fun v -> f v z)
+
+let oks xs =
+  List.fold_left(fun acc x ->
+      match x with
+      | Ok a -> List.append acc [a]
+      | Error _ -> acc
+    ) [] xs
+
+let errors xs =
+  List.fold_left(fun acc x ->
+      match x with
+      | Ok _ -> acc
+      | Error b -> List.append acc [b]
+    ) [] xs
+
+let arrayLefts xs =
+  Array.fold_left(fun acc x ->
+      match x with
+      | Ok a -> Array.append acc [|a|]
+      | Error _ -> acc
+    ) [||] xs
+
+let arrayRights xs =
+  Array.fold_left(fun acc x ->
+      match x with
+      | Ok _ -> acc
+      | Error b -> Array.append acc [|b|]
+    ) [||] xs
+

jscomp/others/belt_Either.mli

@@ -0,0 +1,26 @@
+type ('a, 'b) t =
+  | Ok of 'a
+  | Error of 'b
+
+val ok : 'a -> ('a, 'b) t
+val error : 'b -> ('a, 'b) t
+
+val result : ('a -> 'c) -> ('b -> 'c) -> ('a, 'b) t -> 'c
+
+val map : ('b -> 'c) -> ('a, 'b) t -> ('a, 'c) t
+val (<$>) : ('b -> 'c) -> ('a, 'b) t -> ('a, 'c) t
+val mapLeft : ('a -> 'c) -> ('a, 'b) t -> ('c, 'b) t
+
+val bimap : ('a -> 'c) -> ('b -> 'd) -> ('a, 'b) t -> ('c, 'd) t
+
+val isOk : ('a, 'b) t -> bool
+val isError : ('a, 'b) t -> bool
+
+val toString : ('a -> string) -> ('b -> string) -> ('a, 'b) t -> string
+
+val fold : ('b -> 'c -> 'c) -> 'c -> ('a, 'b) t -> 'c
+
+val oks: (('a, 'b) t) list -> 'a list
+val errors: (('a, 'b) t) list -> 'b list
+val arrayErrors: (('a, 'b) t) array -> 'a array
+val arrayOks: (('a, 'b) t) array -> 'b array

jscomp/others/belt_Result.ml

@@ -27,6 +27,8 @@ var HashSet = 0;
 
 var HashMap = 0;
 
+var Either = 0;
+
 exports.Id = Id;
 exports.$$Array = $$Array;
 exports.SortArray = SortArray;
@@ -40,4 +42,5 @@ exports.MutableSet = MutableSet;
 exports.MutableMap = MutableMap;
 exports.HashSet = HashSet;
 exports.HashMap = HashMap;
+exports.Either = Either;
 /* No side effect */