{-# Language TypeFamilies, DataKinds, TypeOperators, ConstraintKinds, ExistentialQuantification, KindSignatures, UndecidableInstances #-}

module Help where

import Data.Kind

main :: IO ()
main = pure ()

data Entity (cs :: [Type -> Constraint]) = forall a. All cs a => MkEntity a

type family All (cs :: [Type -> Constraint]) (a :: Type) :: Constraint where
  All (c ': cs) a = (c a, All cs a)
  All '[]       a = ()

class Op1 a where
  op1 :: a -> Int

class Op2 a where
  op2 :: a -> Char

data Foo = Foo { fooInt :: Int, fooChar :: Char }

instance Op1 Foo where op1 = fooInt
instance Op2 Foo where op2 = fooChar

example :: Entity [Op1, Op2]
example = MkEntity (Foo 1 'a')