You explained how to make the new world to accommodate the old world.
But what if back in 2015 people wanted to use Classical Monads with Functor and Applicative, without changing the ghc library for monads/applicative/functor?
Could this new technology you discussed today be used for that, if it were available at that time? So that we could still have the classical definition of monad today and at the same time please people who wanted to make the change?