On Sun, 2007-10-14 at 18:14 -0400, Brandon S. Allbery KF8NH wrote:
On Oct 14, 2007, at 17:54 , ntupel wrote:
Now my problem still is, that I don't know how to speed things up. I tried putting seq and $! at various places with no apparent improvement. Maybe I need to find a different data structure for my random module and lazy lists are simply not working well enough here?
Unfortunately I'm not so good at that myself. Even more unfortunately, my understanding is that randomly using seq and/or $! not only usually doesn't help, but can actually make things slower; and to do it right, you need to refer to the "simplified" Core Haskell code generated by GHC. And understanding *that* requires rather more familiarity with Core than I have. :/
A lot of times just unfolding a few evaluations by hand (perhaps mentally) will point out issues readily and readily suggest there solution. After a while you will know what kinds of things are problematic and not write such code to begin with. Unfortunately, this is not something widely and well understood and is not part of almost any of the available educational material for Haskell. Programming in a lazy language is more different than programming in an eager one than almost any resource states.