{-# language DataKinds, TypeFamilyDependencies #-}
module MnistRnnRanked2 where

import Data.Kind (Type)
import GHC.TypeLits (Nat)

type family Value r where

type family Ranked r = (t :: Nat -> Type) | t -> r

rnnMnistZeroR :: Num (Value r) => r
rnnMnistZeroR = undefined

-- foo :: (Num (Value r), Ranked (Value r) 42 ~ Maybe (Value r)) => r
foo :: Ranked (Value r) 42 ~ Maybe (Value r) => r
foo = rnnMnistZeroR