| Both simulations run fine for small values of
| counter "n" but fail badly when "n" becomes big,
| 40,000 say. I happened to have a presentation
| on the subject of Hawk about two months ago, and
| the audience was not much impressed when they saw
| Hugs failing on such simple (in their view)
| examples. I knew beforehand what would happen for
| large "n" and I tried to restrict my presentation
| to small n's, but unfortunately the audience was
| very inquisitive. You see, those people are accustomed
| to running their tests for hours a time, so it
| was natural for them to ask for some big values
| of n.
|
| Not a good publicity for Hugs, unfortunately.
Jan: I don't think you're being very fair. Do you really
know that the failures you demonstrated were due to a bug
in Hugs? Is it possible that they might have been caused
by bugs in the program that you were running? Or perhaps
you simply didn't have Hugs configured with a big enough
heap for the size of the bigger problems that you tried?
If it truly was a bug in Hugs, I hope that you reported
it so that the Hugs maintainers could do something to fix
it?
Joe: As you've observed, the space behavior of Haskell
programs is often very subtle, and hard to understand.
I glanced quickly over your program but didn't see any
immediate signs of problems. My first suggestion would
be that you try using the rudimentary heap profiler that
Hugs provides to see if this gives some insight into the
source of the leak. (You'll probably need to be able
to recompile Hugs with profiling enabled for this.)
Failing that, it might be worth trying to put together
a complete example (program and data) that demonstrates
the problem. I find it rather hard to think about examples
like this in the abstract. Having code that I can actually
run, can make a big difference in situations like this. (I'm
not actually promising that I'll have time to investigate
it myself, but I might, and so might some other readers on
this list.)
All the best,
Mark
