[Haskell-cafe] DataKinds + KindSignatures question

Hello, The following code:

{-# LANGUAGE DataKinds #-} {-# LANGUAGE KindSignatures #-}

import Data.ByteString

data CmdKind = GET | SET

class Serialize (cmd :: CmdKind) where serialize :: cmd -> ByteString

Results in the following error:

wojtek@wojtek-desktop:~/src/he/snip$ ghc dk.hs [1 of 1] Compiling Main ( dk.hs, dk.o )

dk.hs:9:17: Expected a type, but ‘cmd’ has kind ‘CmdKind’ In the type ‘cmd -> ByteString’ In the class declaration for ‘Serialize’

Is this so by design, or should I write it in a different way, or is it just not implemented? -- Kind regards, Wojtek N.