{-# LANGUAGE DataKinds    #-}
{-# LANGUAGE TypeFamilies #-}

import Data.Kind (Type)

main :: IO ()
main = pure ()

-- Some type classes
class Kinded x where
  type Kind x :: Type

class Kinded x => Singlify x where
  data Singleton x :: Kind x -> Type

-- Now some instances for above
data X
data MyKind = A 

instance Kinded X where
  type Kind X = MyKind

instance Singlify X where
  data Singleton X s where
    SingA :: Singleton X 'A