Control.Monad proposal: Add whenJust

[Henning Thielemann]

On Sun, 19 May 2013, Herbert Valerio Riedel wrote:

> On 2013-05-18 16:08:33 +0200, Ian Lynagh wrote:
>
> [...]
>
>> I'd prefer to remove the monomorphic functions, but not to add anything
>> to Prelude.
>
> +1

I'd just leave Prelude as it is, in order to be able to introduce people 
to Haskell without doing any configuration. Experts can configure GHCi to 
import any default set of functions they like.