{-# LANGUAGE DataKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE StandaloneKindSignatures #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE UnliftedNewtypes #-} module Bug where import GHC.Exts type Id :: TYPE r -> TYPE r newtype Id a where MkId :: forall r (a :: TYPE r). a -> Id a idBool :: Id Bool idBool = MkId @LiftedRep @Bool True