[Haskell-cafe] A tale of three shootout entries

Richard Kelsall r.kelsall at millstream.com
Tue Nov 27 14:42:13 EST 2007

Don Stewart wrote:
> There may well have been changes to the strictness analyser that make
> some of the bangs (or most) unnecessary now. Also, its very likely 
> I didn't check all combinations of strict and lazy arguments for the
> optimal evaluation strategy :)

I suspect the optimum details will change again when we get to GHC 6.8.
Yes, I got bored trying different combinations too. A genetic algorithm
that knocks out different combinations might be fun. The ones in rand
seem to make the most difference and I decided the code was easier to
read if I took them all out.

> If it seems to be running consitently faster (and producing better Core
> code), by all means submit. I don't think this is a ghc bug or anything
> like that though: just overuse of bangs, leading to unnecessary work.
> -- Don

It was consistently faster on my machine, but it would be interesting
to compare with the run-times on Sterling's PPC machine. I'll have a
play with Sterling's new program and report.


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