WrappedShow1.hs

newtype WrappedShow1 f a = WrappedShow1 (f a)

instance (Show1 f, Show a) => Show (WrappedShow1 f a) where
  showsPrec x = liftShowsPrec showsPrec showList
  showList x = liftShowList showsPrec showList
  
-- instance Show1 YourThing where
--   liftShowsPrec = reifyShow (const showsPrec) ()
--   liftShowList = reifyShow (const showList) ()
 
data ReifiedShow a = ReifiedShow { reifiedShowsPrec :: Int -> a -> ShowS, reifiedShowList :: [a] -> ShowS }

instance Reifies s (ReifiedShow a) => Show (ReflectedShow a s) where
  showsPrec prec p@(ReflectedShow x) = reifiedShowsPrec (reflect p) prec s
  showList xs = reifiedShowList (reflect (head xs) (coerce xs))
  
newtype ReflectedShow a s = ReflectedShow a

unreflectedShow :: ReflectedShow a s -> proxy s -> a
unreflectedShow (ReflectedShow a) _ = a

reifyShow :: (a -> a -> a) -> a -> (forall (s :: *). Reifies s (ReifiedShow a) => t -> ReflectedShow a s) -> t -> a
reifyShow f z m xs = reify (ReifiedShow f z) (unreflectedShow (m xs))