[Haskell] Types of when and unless in Control.Monad

[Henning Thielemann]

moving to libraries, again ...


On Sun, 22 Apr 2012, Julian Gilbey wrote:

> On Sat, Apr 21, 2012 at 08:28:27PM -0500, Strake wrote:
>> On 21/04/2012, Andreas Abel <andreas.abel at ifi.lmu.de> wrote:
>> > to avoid silly "return ()" statements like in
>> >
>> >    when cond $ do
>> >      monadicComputationWhoseResultIWantToDiscard
>> >      return ()
>> 
>> (when cond ∘ void) monadicComputationWhoseResultIWantToDiscard
>> or
>> when cond $ () <$ monadicComputationWhoseResultIWantToDiscard
>
> How is that simpler than
>
>  when cond monadicComputationWhoseResultIWantToDiscard
>
> which it would be with the suggested new type?


The original poster wanted to make it simpler, others want to let it be 
safer.