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

On 06/06/2011, at 5:51 , KC wrote:

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.

Not as hard as formalising "useful". Ben.