module Err where

data E e a = Failure e | Success a deriving Show

unitE :: a -> E e a
unitE a = Success a 

bindE :: E e a -> (a -> E e b) -> E e b
(Success a) `bindE` k = k a 
(Failure e) `bindE` k = Failure e

failE :: e -> E e a
failE e = Failure e

tryE :: E e a -> (e -> E e a) -> E e a
tryE (Success v) h = Success v
tryE (Failure e) h = h e