MonadPlus is `or` semantics, as is Alternative. It does, indeed, reflect the Applicative/Monad difference.
On Sat, Oct 29, 2011 at 8:02 PM, Gregory Crosswhite <gcrosswh...@gmail.com>wrote: > Hey everyone, > > What is the difference between MonadPlus and Alternative? In my mind, it > would make sense for the difference to be that the former provides "and" > semantics (i.e., x `mplus` y means do both x and y) whereas the latter > provides "or" semantics (i.e., x <|> y means do x or y but not both). > However, when I look at the instances defined for List I see that it is > exactly the same as MonadPlus. > > So is there any difference between the interpretation of MonadPlus and > Alternative, or is the only difference between them that the former applies > to Monad whereas the latter applies to Applicative? > > Also, along similar lines, why does MonadPlus exist when it is essentially > just a special case of Monoid? (That is, any MonadPlus instance could be > equivalently cast as a Monoid instance.) > > Thanks! > Greg > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >
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