[Haskell-cafe] Re: Why?

Stephen Tetley stephen.tetley at gmail.com
Thu Dec 10 12:45:46 EST 2009

Hello David

Apropos the (unfortunately) frosty exchanges that greeted the first
release of UHC a couple of months ago, which argued that UHC wasn't
Haskell because it didn't implement n+k patterns, one could argue (at
least for rhetorical effect) that Haskell plus unsafePerformIO isn't
Haskell, I don't think you'll be able to find unsafePerformIO in the

Best wishes


2009/12/10 David Leimbach <leimy2k at gmail.com>:
> That's not a "safe" way to think of 3rd party libraries.  It is a convenient
> claim for promoting the language, and is probably more often than not the
> case though it does not quite capture the whole truth.  unsafePerformIO can
> exist in any library you import,
> In short unsafePerformIO, while it's "supposed to be" avoided, may not be
> avoided as much as the advice given to do so :-).

More information about the Haskell-Cafe mailing list