#7503: Bug with PolyKinds, type synonyms & 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: Linux | Architecture: x86_64 (amd64)
Failure: GHC rejects valid program | Blockedby:
Blocking: | Related:
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GHC incorrectly rejects this program:
{{{
{-# LANGUAGE ExistentialQuantification, DataKinds, PolyKinds,
KindSignatures, GADTs #-}
module TestConstraintKinds where
import GHC.Exts hiding (Any)
data WrappedType = forall a. WrapType a
data A :: WrappedType -> * where
MkA :: forall (a :: *). AW a -> A (WrapType a)
type AW (a :: k) = A (WrapType a)
type AW' (a :: k) = A (WrapType a)
class C (a :: k) where
aw :: AW a -- workaround: AW'
instance C [] where
aw = aw
}}}
GHC accepts the program when AW is replaced with AW' on that line.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7503>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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