blob: b2f5642ec5de47545f135acabdff71014033aac0 (
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
27
28
29
30
31
32
33
34
35
|
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
module T14991 where
import Data.Kind
type family Promote (k :: Type) :: Type
type family PromoteX (a :: k) :: Promote k
type family Demote (k :: Type) :: Type
type family DemoteX (a :: k) :: Demote k
-----
-- Type
-----
type instance Demote Type = Type
type instance Promote Type = Type
type instance DemoteX (a :: Type) = Demote a
type instance PromoteX (a :: Type) = Promote a
-----
-- Arrows
-----
data TyFun :: Type -> Type -> Type
type a ~> b = TyFun a b -> Type
infixr 0 ~>
type instance Demote (a ~> b) = DemoteX a -> DemoteX b
type instance Promote (a -> b) = PromoteX a ~> PromoteX b
|
