Example of doing a ton of numerical integrals in parallel using monad-par and hmatrix/gsl

integrator.hs

import Numeric.LinearAlgebra
import Numeric.GSL

import Control.Exception
import System.Environment
import Data.Maybe
import Control.Monad.Par
import Control.DeepSeq

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quad = integrateQNG 1E-6

myfn :: Double -> Double
myfn x = x^2        


thefn x =  quad myfn (fst x) (snd x)

lowers = [0.01,0.02..] :: [Double]
uppers = [0.1,0.2..] :: [Double]
my_bounds = zip lowers uppers


f2 x = quad myfn 0.0 x
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main :: IO ()
main = do
  let n = 20

  print (length (runPar $ parMapChunk n thefn (take 8000 my_bounds)))
 

parMapChunk :: (Eq b, NFData b) => Int -> (a -> b) -> [a] -> Par [b]
parMapChunk n f xs = fmap concat $ parMap (map f) (chunk n xs)

chunk :: Int -> [a] -> [[a]]
chunk _ [] = []
chunk n xs = as : chunk n bs where (as,bs) = splitAt n xs