Parallel Test

import Control.Parallel.Strategies
import Control.Monad
import Control.DeepSeq

sums :: [Int] -> Int
sums xs = s + ds
    where
        s = foldl (+) 0 xs
        ds = foldl (\x acc -> (x*2) + acc) 0 xs

sumsP :: [Int] -> Int
sumsP xs = let fXs = force xs in
    (\(x,y) -> x + y) . runEval $ do
        s'  <- rpar $ foldl (+) 0 fXs
        ds' <- rpar $ foldl (\x acc -> (x*2) + acc) 0 fXs
        rseq s'; rseq ds'
        return (s',ds')

main = print $ sumsP [1..5000000]