#7269: GeneralizedNewtypeDeriving and PolyKinds
------------------------------+---------------------------------------------
Reporter: dreixel | Owner: dreixel
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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The following code
{{{
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
class C (a :: k)
instance C Int
newtype MyInt = MyInt Int deriving C
}}}
fails with this error:
{{{
Cannot derive well-kinded instance of form `C k (MyInt ...)'
Class `C' expects an argument of kind `k'
In the newtype declaration for `MyInt'
}}}
I believe this should work, and I think I know what's going on. I'm
working on it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7269>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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