blob: 2c1f484f47ac2899b11c44ff7527fd5159c038a8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
|
{-# LANGUAGE RebindableSyntax, MultiParamTypeClasses #-}
-- Trac #1537
module Foo where
import Prelude hiding (Monad(..))
class Bind m1 m2 m3 where
(>>=) :: m1 a -> (a -> m2 b) -> m3 b
class Return m where
return :: a -> m a
fail :: String -> m a
instance Bind Maybe [] [] where
Just x >>= f = f x
Nothing >>= f = []
instance Return [] where
return x = [x]
fail _ = []
should_compile :: [Int]
should_compile = do
a <- Just 1
[a]
|
