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

On Wed, 10 Apr 2019, 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

https://hackage.haskell.org/package/utility-ht-0.0.14/docs/Data-Monoid-HT.ht...