blob: ebc4dc7cad16cb48eb82cf371943dff7cabc6f1e (
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
36
37
38
39
40
41
42
43
44
45
|
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE FlexibleInstances, UndecidableInstances, FunctionalDependencies #-}
-- The code from the ticket lacked necessary extension FlexibleContexts
-- which crashed the compiler with "GHC internal error"
-- This test case reproduces that scenario
{- # LANGUAGE FlexibleContexts #-}
module T12055a where
import GHC.Base ( Constraint, Type )
import GHC.Exts ( type (~~) )
type Cat k = k -> k -> Type
class Category (p :: Cat k) where
type Ob p :: k -> Constraint
class (Category (Dom f), Category (Cod f)) => Functor (f :: j -> k) where
type Dom f :: Cat j
type Cod f :: Cat k
functor :: forall a b.
Iso Constraint (:-) (:-)
(Ob (Dom f) a) (Ob (Dom f) b)
(Ob (Cod f) (f a)) (Ob (Cod f) (f b))
class (Functor f , Dom f ~ p, Cod f ~ q) =>
Fun (p :: Cat j) (q :: Cat k) (f :: j -> k) | f -> p q
instance (Functor f , Dom f ~ p, Cod f ~ q) =>
Fun (p :: Cat j) (q :: Cat k) (f :: j -> k)
data Nat (p :: Cat j) (q :: Cat k) (f :: j -> k) (g :: j -> k)
type Iso k (c :: Cat k) (d :: Cat k) s t a b =
forall p. (Cod p ~~ Nat d (->)) => p a b -> p s t
data (p :: Constraint) :- (q :: Constraint)
|
