Philip Armstrong wrote:
On Mon, Feb 18, 2008 at 05:56:41PM +0000, Adrian Hey wrote:
Philip Armstrong wrote:
On Sun, Feb 17, 2008 at 10:01:14PM +0000, Adrian Hey wrote:
BTW, I find this especially ironic as fromDistinctAscList is the perfect example what I was talking about in another thread (continuation passing madness caused by an irrational fear of stack use).
In *some* cases, continuation passing can be quite a bit faster than other approaches IIRC. I haven't looked at this bit of code though.
Can you or anyone else give an example?
I think I was thinking of this:
http://r6.ca/blog/20071028T162529Z.html
but can't be entirely sure. Sorry!
Perhaps I should say can someone provide an example and explain why they believe it is faster. That isn't to say I doubt the measurements taken with that particular code, but I must say that if transforming code that uses the "hardware accelerated" continuation passing (by that I mean the machine stack of course) to explicit continuations on the heap is generally faster, there must be something very wrong in stack land. But perhaps there is? Interestingly, if you allow sufficient stack space for Grzegorz version (+64M) it does terminate, but it's still much slower than the version you provided (about 30 times slower). I don't know if this slow down is due only to the stack use, or whether both the stack use and the slow down are just different artefacts of the problem Bertram mentioned. Regards -- Adrian Hey