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|
open Pervasiveext
open Listext
type ('a,'b) t = Left of 'a | Right of 'b
module Monad = Monad.M2.Make (struct
type ('a, 'b) m = ('b, 'a) t
let bind value f =
match value with
| Left value -> Left value
| Right value -> f value
let return value = Right value
end)
let left x = Left x
let right x = Right x
let is_left = function
| Left _ -> true
| Right _ -> false
let is_right x = not ++ is_left $ x
let to_option = function
| Right x -> Some x
| Left _ -> None
let cat_right l = List.unbox_list ++ List.map to_option $ l
let join = function
| Right (Right x) -> Right x
| Left x -> Left (Left x)
| Right (Left x) -> Left (Right x)
let swap = function
| Right x -> Left x
| Left x -> Right x
let of_exception f =
try Right (f ())
with e -> Left e
|
