singletons-0.8: Singletons/TypeRepStar.hs

{- Singletons/TypeRepStar.hs

(c) Richard Eisenberg 2012
eir@cis.upenn.edu

This file contains the definitions for considering TypeRep to be the demotion
of *. This is still highly experimental, so expect unusual results!

-}

{-# LANGUAGE RankNTypes, TypeFamilies, KindSignatures, FlexibleInstances,
             GADTs, UndecidableInstances, ScopedTypeVariables #-}

module Singletons.TypeRepStar where

import Singletons.Lib
import Data.Typeable

data instance Sing (a :: *) where
  STypeRep :: Typeable a => Sing a

sTypeRep :: forall (a :: *). Typeable a => Sing a
sTypeRep = STypeRep

instance Typeable a => SingI (a :: *) where
  sing = STypeRep
instance SingE (a :: *) where
  type Demote a = TypeRep
  fromSing STypeRep = typeOf (undefined :: a)
instance SingKind (Any :: *) where
  singInstance STypeRep = SingInstance