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Consider the following modules:

module PolykindTH where

import Language.Haskell.TH

makeSList :: Q [Dec]
makeSList = do
  a <- newName "a"
  k <- newName "k"
  return [TySynD (mkName "SList") [KindedTV a (AppT ListT (VarT k))]
                 (AppT (ConT (mkName "Sing")) (VarT a))]
-- makes "type SList (a :: [k]) = Sing a"

{-# LANGUAGE PolyKinds, TypeFamilies, DataKinds, TemplateHaskell #-}

module Polykind where

import PolykindTH

data family Sing (a :: k)

$( makeSList )

When these modules are compiled, the resultant Iface file fails to load when code attempts to use the modules. To check this, I packaged this up with a cabal file, registered the package with my GHC (7.5.20120620), and then attempted to compile the following:

import Polykind

foo :: SList a -> Bool
foo = undefined

Here is the error:

Declaration for SList:
  Iface type variable out of scope:  k
Cannot continue after interface file error

I have attached a tarball of my cabal package for ease of testing.

Trac metadata

Trac field	Value
Version	7.5
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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