On Mon, 17 Jan 2005 10:48:18 -0600, jekwtw
I'm putting together a script to gather run-time stats for some functions I'm working with, and I'm having a terrible time. My strategy is to evaluate a function a number of times and compute the difference between the elapsed CPU time before and after the repeated calls.
timeNReps :: (a -> b) -> a -> Int -> FilePath -> IO () timeNReps func arg reps fileName = do t0 <- System.CPUTime.getCPUTime runNReps func arg reps t1 <- System.CPUTime.getCPUTime appendFile fileName ((showMS (t1 - t0)) ++ "\n") where showMS n = show (n `quot` 1000000000)
showMS just converts the pico-second result into milli-seconds and stringifies it.
runNReps is an IO program (do sequence) that is intended to call the function and tail-call itself a given number of times:
runNReps :: (Int -> a) -> Int -> Int -> IO () runNReps f x todo | todo > 0 = do let junk = (f x) runNReps f x (todo - 1) | otherwise = return (())
Haskell is a non-strict language which means that 'junk' wont be evaluated since it's not necessary for the function to terminate. Check 'replicateM_' from Control.Monad.
runNReps :: Int -> IO a -> IO () runNReps = replicateM_
-- Friendly, Lemmih