{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeFamilies, FunctionalDependencies, UndecidableSuperClasses #-}

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 = ()

data DataID = DataID

class All cs a => HasDataID cs a | a -> cs where
  getDataID :: a -> DataID
  getDependencies :: a -> [Entity (HasDataID cs:cs)]

class GetMessage a where
  getMessage :: a -> Int

data Foo = Foo
data Bar = Bar

instance GetMessage Bar where
  getMessage _ = 1

instance HasDataID '[GetMessage] Bar where
  getDataID _ = DataID
  getDependencies _ = []

instance HasDataID '[GetMessage] Foo where
  getDataID _ = DataID
  --getDependencies :: (c ~ getMessage) => Foo -> [Entity [HasDataID, GetMessage]]
  getDependencies _ = [MkEntity Bar]