Proposal: add ifM and whenM to Control.Monad

[Bardur Arantsson]

On 2014-04-21 17:47, Edward Kmett wrote:
> I, for one, could get behind just taking ifM, whenM, unlessM for these
> operations, proper naming conventions aside.
> 
> They've been independently reinvented in 60+ packages with these exact
> names.
> 
> If we do this, over time we'll save another 60+ packages the trouble of
> doing the same thing.

+1 (for the proposal, based on exactly the above summary)