[Haskell-beginners] Re: Forcing evalation in the IO Monad

[Daniel Fischer]

Am Freitag 16 April 2010 16:25:08 schrieb Heinrich Apfelmus:
> Philip Scott wrote:
> > What I want is something like putStrLn that doesn't print anything,
> > and takes any type as its input, evaluates it to normal form and then
> > does nothing else. It might be called something like 'evaluate' have a
> > type like this
> >
> > evaluate :: a -> IO()
>
> With Hoogle, you can search for types:
>
>    http://haskell.org/hoogle/?hoogle=a+-%3E+IO+%28%29
>
> 12th result from the top.

That evaluates only to WHNF.

Control.DeepSeq.rnf seems to be closer, but requires NFData instances.

>
>
> Regards,
> Heinrich Apfelmus