Allow deriving multiparameter type classes with representationally equal arguments

This currently works

{-# Language DerivingStrategies, MultiParamTypeClasses, FunctionalDependencies, GeneralizedNewtypeDeriving #-}

import Data.Kind
import Data.Functor.Identity

class SIEVE f p | p -> f where
  sIEVE :: p a b -> a -> f b

instance SIEVE Identity (->) where
  sIEVE = (Identity .)

newtype ARR a b = ARR (a -> b)
  deriving newtype 
    (SIEVE Identity)

But what if I want a Sieve I ARR instance, for newtype I a = I a (which is representationally equal to newtype Identity a = Identity a)?

{-# Language DerivingStrategies, MultiParamTypeClasses, FunctionalDependencies, GeneralizedNewtypeDeriving, RankNTypes, TypeApplications, ScopedTypeVariables, InstanceSigs #-}

import Data.Kind
import Data.Functor.Identity
import Data.Coerce

class SIEVE f p | p -> f where
  sIEVE :: p a b -> a -> f b

instance SIEVE Identity (->) where
  sIEVE = (Identity .)

newtype ARR a b = ARR (a -> b)
  deriving newtype
    (SIEVE I)

newtype I a = I a

generating the following code (this is basically to code generated before, except replacing some Identitys with Is

instance SIEVE I ARR where
  sIEVE :: forall a b. ARR a b -> (a -> I b) 
  sIEVE
    = coerce
      @((a -> b) -> a -> Identity b)
      @(ARR a b  -> a -> I b)
      sIEVE

GHC should be able to recover Identity due to the functional dependency.