cannot derive new-typeable instances for promoted data types taking parameters

Hi,

The following code shows the issue:

{-# LANGUAGE DataKinds, DeriveDataTypeable, KindSignatures, PolyKinds, StandaloneDeriving #-}
import Data.Typeable
import GHC.TypeLits

data T (a :: [*]) = T deriving (Typeable)

t = T :: T [Int, Double]

deriving instance Typeable '[]
{-

*Main> typeOf t

<interactive>:24:1:
    No instance for (Typeable (* -> [*] -> [*]) ((':) *))
      arising from a use of ‛typeOf’
    In the expression: typeOf t
    In an equation for ‛it’: it = typeOf t
-}

ghc7.7-20131004 doesn't allow either of the following:

deriving instance (Typeable a, Typeable b) => Typeable (a ': b)
-- or
deriving instance Typeable (':)

On ghc-7.6 I could write my own instance Typeable (T a), but this has been disabled it seems.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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