Draft: Make reify poly-kinded

fast/Data/Reflection.hs

@@ -11,6 +11,9 @@
 {-# LANGUAGE Rank2Types #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeOperators #-}
+#if __GLASGOW_HASKELL__ < 806
+{-# LANGUAGE TypeInType #-}
+#endif
 #ifdef MIN_VERSION_template_haskell
 -- TH-subset that works with stage1 & unregisterised GHCs
 {-# LANGUAGE TemplateHaskellQuotes #-}
@@ -137,6 +140,10 @@ import System.IO.Unsafe
 import Unsafe.Coerce
 #endif
 
+#if __GLASGOW_HASKELL__ < 806
+import Data.Kind
+#endif
+
 #if MIN_VERSION_base(4,18,0)
 import qualified GHC.TypeNats as TN
 #endif
@@ -161,11 +168,11 @@ class Reifies s a | s -> a where
   -- reified type.
   reflect :: proxy s -> a
 
-newtype Magic a r = Magic (forall (s :: *). Reifies s a => Proxy s -> r)
+newtype Magic a r k = Magic (forall (s :: k). Reifies s a => Proxy s -> r)
 
 -- | Reify a value at the type level, to be recovered with 'reflect'.
-reify :: forall a r. a -> (forall (s :: *). Reifies s a => Proxy s -> r) -> r
-reify a k = unsafeCoerce (Magic k :: Magic a r) (const a) Proxy
+reify :: forall a r k. a -> (forall (s :: k). Reifies s a => Proxy s -> r) -> r
+reify a k = unsafeCoerce (Magic k :: Magic a r k) (const a) Proxy
 {-# INLINE_UNSAFE_COERCE reify #-}
 
 instance KnownNat n => Reifies n Integer where