ben.franksen:
> Luke Andrew wrote:
> > main = do print $ zipWith (+) (fiblist2 37 `par` fiblist1 37)
> > (fiblist2 37)
> >
> > compilation & testing:
> >
> > [EMAIL PROTECTED]:~/mcls$ ghc -O2 -threaded --make test2
> >
> > [EMAIL PROTECTED]:~/mcls$ time ./test2 +RTS -N1
> > [2,2,4,6,10,16,26,42... ...405774,18454930,29860704,48315634]
> >
> > real 0m15.294s
> > user 0m15.196s
> > sys 0m0.013s
> >
> > [EMAIL PROTECTED]:~/mcls$ time ./test2 +RTS -N2
> > [2,2,4,6,10,16,26,42... ...405774,18454930,29860704,48315634]
> >
> > real 0m15.268s
> > user 0m15.169s
> > sys 0m0.013s
>
> This is due to lazyness: 'fiblist2 37' does not evaluate the whole resulting
> list, so the thread spawned by 'par' will almost immediately return.
>
> Take a look at Control.Parallel.Strategies, the 'parList' combinator is
> probably what you need here. To get a feel what this 'strategies' stuff is
> all about, it is a good idea to read (or at least skim over) the
> accompanying paper, just google for "Algorithm + Strategy = Parallelism".
or 'rnf' on the result.
rnf x `par` y
is the basic "fully strict" strategy.
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