On 13/03/2007, at 17:46, Jefferson Heard wrote:
Simon will probably chime in on it as well, but his paper on the subject is the best there is:
http://research.microsoft.com/~simonpj/Papers/strategies.ps.gz
It does work in GHC 6.6 very nicely. You can try it with the following naive fib function, extracted from the paper mentioned above: \begin{code} import Control.Parallel import System.Environment import Fib main = do (x:_) <- getArgs print$ pfib (read x) pfib 0 = 1 pfib 1 = 1 pfib n = n1 `par` n2 `seq` n1+n2+1 where (n1,n2) = (pfib(n-1), pfib(n-2)) \end{code} pep:~/code/snippets/Parallelism$ ghc --make -O Main -threaded pep:~/code/snippets/Parallelism$ time src/Main 33 11405773 real 0m1.444s user 0m1.343s sys 0m0.020s pep:~/code/snippets/Parallelism$ time src/Main 33 +RTS -N2 11405773 real 0m0.764s user 0m1.367s sys 0m0.030s Got a speedup of 100%, and didn't use threads at all. Yay! pepe