Am Samstag 13 März 2010 21:42:12 schrieb legajid:
After a few efforts, i've understood my mistake. I now write : t1d <- gettime putStrLn ("Methode 1 : " ++ show t1d) let t1=last (listeprem 5000) putStrLn (" " ++ show t1) t1f <- gettime putStrLn (" " ++ show t1f)
and that's ok.
What i feel shocking is having io code mixed within calculation code.
Right, that's not so good.
I think it's possible to force calculation of t1d, t1 and t1f before (or without) displaying their values (i just want t1f - t1d). But how to make it ?
Depends on the types. Often a bang-pattern or a `seq` is enough, for other types, you might want to look at Control.DeepSeq and Control.Parallel.Strategies. NFData, rnf, deepseq, using, demanding, ... may help you. For lists, sometimes (length list) `seq` whatever is enough, without needing strategies.
Thanks, Didier