#7527: Couldn't match kind `*' with `*' with PolyKinds & GADTs.
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Reporter: Ashley Yakeley | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler (Type checker)
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Blockedby:
Blocking: | Related:
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{{{
{-# LANGUAGE ExistentialQuantification, DataKinds, PolyKinds,
KindSignatures, GADTs #-}
module TestKindMatching where
import GHC.Exts hiding (Any)
data WrappedType = forall a. WrapType a
data T (wt :: WrappedType)
class P (p :: WrappedType -> *) where
get :: T wt -> p wt
data W :: (k -> *) -> WrappedType -> * where
MkW :: forall (f :: k -> *) (a :: k). (f a) -> W f (WrapType a)
instance P (W (f :: * -> *)) where
get = get
thing :: forall (a :: *) (f :: * -> *). T (WrapType a) -> f a
thing t = case (get t) of
MkW cw -> cw
}}}
{{{
$ ghc -c TestKindMatching.hs
TestKindMatching.hs:20:9:
Couldn't match kind `*' with `*'
Expected type: a1
Actual type: a
Kind incompatibility when matching types:
a :: *
a1 :: *
In the pattern: MkW cw
In a case alternative: MkW cw -> cw
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7527>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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