Re: Proposal: add Control.Monad.whenJust ∷ (Monad m) ⇒ Maybe α→(α→ m ()) → m ()

30 Nov 2011


      On 11/30/2011 02:11 PM, Liyang HU wrote:
...
This particular pattern crops up a lot for me. Does it for anyone else?
I (half-heartedly) propose adding to Control.Monad the following:
...
-- | A variation of 'when' for 'Maybe a'.
whenJust :: (Monad m) =>  Maybe a ->  (a ->  m ()) ->  m ()
whenJust =  flip (maybe (return ()))
We already have it. See Data.Foldable.forM_

Re: Proposal: add Control.Monad.whenJust ∷ (Monad m) ⇒ Maybe α→(α→ m ()) → m ()

Mikhail Vorozhtsov