[Haskell-cafe] Use unsafePerformIO to catch Exception?

Jonathan Cast jonathanccast at fastmail.fm
Wed Mar 25 12:17:38 EDT 2009

On Wed, 2009-03-25 at 09:15 -0700, Donn Cave wrote:
> Quoth Lennart Augustsson <lennart at augustsson.net>:
> > Some examples of what might happen:
> OK, these are interesting phenomena.  From a practical point of view,
> though, I could see someone weighing the potential costs and benefits
> of a exception handler outside IO like this, and these effects might
> not even carry all that much weight.

Well, sure.  From a purely `practical' point of view, I don't know why
you would even use a purely functional language (as opposed to trying to
minimize side effects in an impure language).  But if you're not
concerned about purity, or ease of equational reasoning, or accuracy of
a wide range of compiler transformations/optimizations/because it makes
the generated code pretty to sort the formal parameters by name before
forcing them-implementation decisions, then please do not use Haskell.
There are many other languages that are suitable for what you want to
do, and it would be a courtesy to those of us who *do* use Haskell
because it is purely functional, not to have to explicitly exclude your
library from our picture of the language's capabilities.


More information about the Haskell-Cafe mailing list