[Haskell-cafe] Can it be proven there are no intermediate "useful" type classes between Applicative Functors & Monads?

[KC]

If new intermediate classes crop up then there would be no point in fixing

class (Applicative m) => Monad m where

since it would have to be changed if new intermediate classes are found.

I realize non-existence proofs are hard.

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Regards,
KC