blob: 68bae857cfb3870b96a08cb1dd236d0601517343 (
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
|
{-# LANGUAGE GeneralizedNewtypeDeriving, TypeFamilies, FlexibleContexts, FlexibleInstances #-}
module T2850 where
import Data.Kind (Type)
class K a where
bar :: a -> a
class K (B a) => M a where
data B a :: Type
foo :: B a -> B a
instance M Bool where
data B Bool = B1Bool Bool | B2Bool Bool
foo = id
instance K (B Bool) where
bar = id
-- The 'deriving K' gives the (K (B Int)) instance
-- needed for the superclasses of M
instance M Int where
newtype B Int = BInt (B Bool) deriving K
foo = id
|
