[Haskell-beginners] Early return in IO monad

[Brent Yorgey]

On Sat, Aug 31, 2013 at 08:05:26PM +0200, Nathan Hüsken wrote:
> Hey,
> 
> Is it somehow possible to return "early" in a do block of the IO monad?
> The eqivalent do in C:
> 
> void doBlock() {
>     if (some preCondition) {
>       return;
>     }
>     ...
> }
> 
> ???

Nope.  But you can say

  do ...
     when (not (some condition)) $ do
       the
       rest
       of
       the
       stuff

You can even indent "the rest of the stuff" directly under the 'when'
if you like, though IMO that may be a bit confusing.

-Brent