darcs patch: Add justIf to Data.Maybe
jon.fairbairn at cl.cam.ac.uk
Sat Aug 22 10:15:39 EDT 2009
Joachim Breitner <mail at joachim-breitner.de> writes:
> Am Samstag, den 22.08.2009, 10:13 +0100 schrieb Jon Fairbairn:
>> Joachim Breitner <mail at joachim-breitner.de> writes:
>> > I propose the attached change, with a discussion timeframe until end of
>> > September. The corresponding ticket is
>> > http://hackage.haskell.org/trac/ghc/ticket/3446
>> > Thanks,
>> > Joachim
>> I have been meaning to get round to proposing check for Data.Monad:
>> > check :: (MonadPlus m) => (a -> Bool) -> a -> m a
>> > check p a
>> > | p a = return a
>> > | otherwise = mzero
>> Now justIf = flip (check . const)
>> So I suggest that it would be better to add check first(, and then
>> possibly switch the order of arguments to justIf).
> are you proposing that, if check is available, no justIf is needed in
> the libraries?
I wouldn't be proposing that, having promised not to post on the topic
of naming short functions for ten years.
> Or are you just proposing a different implementation?
I /am/ proposing that. I suppose I have to work out how to make a proper
proposal for the addition of check?
Jón Fairbairn Jon.Fairbairn at cl.cam.ac.uk
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