IO Bool -> Bool

[Brandon Michael Moore]

On Thu, 14 Aug 2003, Wolfgang Jeltsch wrote:

> On Thursday, 2003-08-14, 17:05, CEST, Kevin S. Millikin wrote:
> > On Wednesday, August 13, 2003 11:20 PM, Tn X-10n
> > [SMTP:kawairashii@hotmail.com] wrote:
> > >  is it possible to convert IO Bool to Bool?
> >
> > Sure.  Which Bool do you want?  True?
> >
> > > toTrue :: IO Bool -> Bool
> > > toTrue x = True
> >
> > Or False?
> >
> > > toFalse :: IO Bool -> Bool
> > > toFalse x = False

There's also

boolFromIO :: IO Bool -> Bool
boolFromIO = boolFromIO

if you want to be even less useful :)

> I wouldn't call these *conversion* functions because they don't look at their
> argument.
>
> > Maybe that's not what you had in mind.
>
> Surely not.
>
> Wolfgang

I'm surprise nobody has mentioned unsafePerformIO (:: IO a -> a).
As the name suggests, it isn't referentially transparent.

Are you sure you need a function of type IO Bool -> Bool? What are you
trying to do?

Brandon