[Haskell-cafe] [Haskell] Functor => Applicative => Monad

John Smith voldermort at hotmail.com
Thu Dec 16 19:03:45 CET 2010

On 15/12/2010 14:31, Lennart Augustsson wrote:
> Yes, I think there should be a MonadFail distinct from MonadPlus.
> Some types, like IO, are not in MonadPlus, but have a special implementation of the fail method.
> Personally, I think fail should just be removed, but that would break existing code.
> The fail method was introduced for the wrong reasons (better error messages was the excuse).

Which other monads (other than MonadPlus subclasses) define fail?

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