looking for data structure advice

[Tomasz Zielonka]

On Fri, Dec 12, 2003 at 08:55:59PM +0000, Graham Klyne wrote:
> At 14:17 12/12/03 -0500, Derek Elkins wrote:
> >This will also provide a migration path if you want a more featureful
> >monad.  (or_maybe is mplus, fail or mzero can be used for Nothing when
> >you explicitly want to fail).
> 
> Is this or_maybe (and friends) actually defined in any of the standard 
> libraries?  (Google found only one hit, in an old IRC log.)

mplus and mzero are methods in class MonadPlus, which you'll found in
module Monad. There is an instance of MonadPlus for Maybe.

Best regards,
Tom

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