I'm -1 on this just because it is a rather awkward idiom to use, the name
doesn't really make much sense and it is less fundamental than many of the
things we've rejected on those grounds in the past. ;)
-Edward
On Thu, Jul 25, 2013 at 3:16 PM, John Wiegley
The function is:
om f m = (m >>=) . flip f
Allowing this typical usage:
om when (return True) $ print "Hello"
Thus, it allows one to do away with the monadic variants of pure functions, such as "whenM", "unlessM", etc.:
whenM = om when unlessM = om unless
"om" gets even more handy when you want to apply a monadic function to a monadic value in yet another monad:
>>> om for_ (return (Just True)) print True
Rather than the typical (which I must have written hundreds of times by now):
mx <- return (Just x) for_ mx $ \x -> {- use x... -}
A rider to this proposal is to also add "nom = flip om", but I can live without that one. "om", however, is handy enough that I've started locally defining in all the modules where I find myself now reaching for it.
-- John Wiegley FP Complete Haskell tools, training and consulting http://fpcomplete.com johnw on #haskell/irc.freenode.net
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