Commit 921ebc9f authored by Simon Peyton Jones's avatar Simon Peyton Jones

Test Trac #12055

parent e064f501
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeInType #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeInType #-}
-- The code from the ticket lacked these extensions,
-- but crashed the compiler with "GHC internal error"
-- It doesn't crash now; and in this test case I've added
-- the extensions, which makes it compile cleanly
{-# LANGUAGE FlexibleContexts, FlexibleInstances, UndecidableInstances, FunctionalDependencies #-}
module T12055 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)
......@@ -148,3 +148,4 @@ test('T11648b', normal, compile_fail, [''])
test('KindVType', normal, compile_fail, [''])
test('T11821', normal, compile, [''])
test('T11640', normal, compile, [''])
test('T12055', normal, compile, [''])
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment