On Thu, Dec 16, 2010 at 12:03 PM, John Smith <volderm...@hotmail.com> wrote: > 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? >
STM is in MonadPlus, but I don't think pattern-match failure should be the same as STM.retry. Antoine _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe