looking for data structure advice

Graham Klyne gk at ninebynine.org
Mon Dec 15 08:55:10 EST 2003

I apologize... my question was unclear.

It was not the standard MonadPlus class and functions that I was asking 
about, but the specific instance for Maybe (i.e. or_maybe).  As it happens, 
a couple of times in the past couple of weeks, I might have used such a 
function if it were available in the standard libraries.

(Thanks, anyway!)


At 11:30 14/12/03 +0100, Tomasz Zielonka wrote:
>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,
>.signature: Too many levels of symbolic links

Graham Klyne
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