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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #5937
Closed
Open
Issue created Mar 13, 2012 by Richard Eisenberg@raeDeveloper

Kind variables not allowed in data declaration kind annotation

GHC won't accept kind variables stated directly in a data declaration. For example, the following does not compile:

data SMaybe :: (k -> *) -> Maybe k -> * where
  SNothing :: SMaybe s 'Nothing
  SJust :: s a -> SMaybe s ('Just a)

However, the following does compile:

data SMaybe' (s :: k -> *) (m :: Maybe k) where
  SNothing' :: SMaybe' s 'Nothing
  SJust' :: s a -> SMaybe' s ('Just a)
Trac metadata
Trac field Value
Version 7.5
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
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