[Haskell-cafe] how unsafe is this?

[Donald Bruce Stewart]

benc:
> 
> I've defined a helper function to let me do regexps in functional style:
> 
> > sed exp str = unsafePerformIO $ do
> >  regexp <- regcomp exp 0
> >  regexec regexp str
> 
> Is this always safe? or where is it not?
> 
> (I'm using any one regexp more than once so it doesn't bother me that it 
> compiles each time)

Hopefully regex(3) is referentially transparent, so this should be fine :)

-- Don