Re: [Haskell-cafe] Foreign function performance: monadic vs pure

Serguei Son writes:

Felipe Almeida Lessa writes:

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On Mon, Apr 11, 2011 at 10:14 AM, Maciej Marcin Piechotka wrote:

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main = mapM (\x -> return $! c_sin_u) [1..n] 0.012 s

This should be

main = mapM (\x -> return $! c_sin_u x) [1..n]

So if I must use a safe function returning IO a, there is no way to improve its performance? To give you a benchmark, calling gsl_ran_ugaussian a million times in pure C takes only a second or two on my system.

Also, please note that I can force the evaluation of c_sin, e.g. mapM (return . c_sin) [1..n] >>= (print $ foldl' (+) 0) And it will still execute reasonably fast.