Proposal: Add isLeft/isRight to Data.Either

[Erik Hesselink]

On Fri, Dec 7, 2012 at 9:29 AM, Bas van Dijk <v.dijk.bas at gmail.com> wrote:
> On 6 December 2012 23:05, Evan Laforge <qdunkan at gmail.com> wrote:
>>>>   - I often use the 'when'-like combinator 'whenJust' in monadic code:
>>>>
>>>>      whenJust :: Monad m => Maybe a -> (a -> m ()) -> m ()
>>>>      whenJust (Just x) a = a x
>>>>      whenJust _        _ = return ()
>>>
>>>
>>> +1. whenJust is defined also in Agda.Utils.Monad, should also added to
>>> Control.Monad.
>>
>> Off topic, but I have whenJust in my local library too, and I use it
>> all the time.
>
> In a project at work:
>
> $ grep -r whenJust --include=\*.hs . | wc -l
> 27

There is no need to define whenJust, since it is just a specialization
of forM_ from Data.Foldable.

Erik