[Haskell-cafe] MonadPlus

Bryan O'Sullivan bos at serpentine.com
Fri May 9 15:48:29 EDT 2008

Andrew Coppin wrote:
> But here's a
> question: what is the purpose of the MonadPlus class?

It gives you a way of working with monads as monoids.  Consider a Parsec

metasyntactic = text "foo" `mplus` text "bar" `mplus` text "baz"

You'll get back whichever one matched, in left-to-right-order, or mzero
(a parse failure) if all of them fail.


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