Re: Proposal: Add Chris Done's "om" combinator to Control.Monad

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Bryan O'Sullivan writes:

Sure, this is a common pattern. But the name is terrible, and it's not clear to me that the functionality is a useful generalization. Why not advocate for whenM instead?

whenM :: Monad m => m Bool -> m () -> m ()

The entire point of the proposal is that "om" subsumes such specialized functions, saving you from having to use whenM, unlessM, etc. You simply put "om" (or whatever name you want to call it, the name wasn't the objective of this proposal) in front of functions you already know and use, and suddenly they become able to accept monadic arguments where they couldn't before. Consider the "om forM_" example from before, which is actually quite handy and clarifying, once you know how to read the combinator. -- John Wiegley FP Complete Haskell tools, training and consulting http://fpcomplete.com johnw on #haskell/irc.freenode.net