Re: Proposal: Add Data.Monoid.mwhen :: Monoid m => Bool -> m -> m

On 2019-04-10 11:36 a.m., James Ashwell wrote:

This would mimic the behaviour of Control.Monad.when for monoids rather than applicatives.

mwhen :: Monoid m => Bool -> m -> m

mwhen b a | b         = a | otherwise = mempty

Or shorter mwhen = bool (const mempty) id I'd rather construct the right-hand side than memorize the left, so -1 from me.