[Haskell] IO question

Keith Wansbrough Keith.Wansbrough at cl.cam.ac.uk
Fri Jun 11 08:50:06 EDT 2004

> On Fri, Jun 11, 2004 at 01:23:11PM +0200, Tom Hofte wrote:
> > I want to have a function that unpack an IO.
> > I should have the type: IO a -> a.
> > Is this possible?
> There is unsafePerformIO, but before you use it, think - do you
> really, really want to use it and you really, really know what the
> consequences can be? Perhaps you could tell us what it is that you think
> you need unsafePerformIO for? Maybe it can be done without it?

It really should be a list Rule that we don't mention unsafePerformIO
to newbies.  It should be obvious from the post that unsafePerformIO
is *not* what the poster wants, so telling them about it will just
confuse them.  The wiki pointer is much more useful.

(and the ghost of Launchbury whispers in my ear that this is the
Haskell list, and "unsafePerformIO is not Haskell"!).

--KW 8-)

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