On Sat, Aug 23, 2008 at 6:15 PM, Daniel Fischer
Am Samstag, 23. August 2008 23:17 schrieb Thomas Davie:
I'd be interested to see your other examples -- because that error is not happening in Haskell! You can't argue that Haskell doesn't give you no segfaults, because you can embed a C segfault within Haskell.
Use ST(U)Arrays, and use unsafeWrite because you do the indexchecking yourself. Then be stupid and confuse two bounds so that you actually write beyond the array bounds. I've had that happen _once_. But if you explicitly say you want it unsafe, you're prepared for it :)
Which illustrates the point that it's not type safety that protects us from segfaults, so much as bounds checking, and that's got a non-trivial runtime cost. At least, most segfaults that *I've* caused (in C or C++) have been from overwriting the bounds of arrays, and that's precisely the problem that Haskell does *not* solve using its type system. There have attempts to do so, but I've not heard of instances where they have been used in real programs. David