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Timing computations

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See also [[Timing out computations]].
 
See also [[Timing out computations]].
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Timing a pure computation:
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<haskell>
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import Text.Printf
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import Control.Exception
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import System.CPUTime
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import Control.Parallel.Strategies
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import Control.Monad
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import System.Environment
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lim :: Int
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lim = 10^6
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time :: (Num t, NFData t) => t -> IO ()
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time y = do
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    start <- getCPUTime
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    replicateM_ lim $ do
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        x <- evaluate $ 1 + y
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        rnf x `seq` return ()
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    end  <- getCPUTime
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    let diff = (fromIntegral (end - start)) / (10^12)
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    printf "Computation time: %0.9f sec\n" (diff :: Double)
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    printf "Individual time: %0.9f sec\n" (diff / fromIntegral lim :: Double)
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    return ()
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main = do
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    [n] <- getArgs
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    let y = read n
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    putStrLn "Starting..."
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    time (y :: Int)
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    putStrLn "Done."
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</haskell>
  
 
[[Category:Code]]
 
[[Category:Code]]
 
[[Category:Idioms]]
 
[[Category:Idioms]]
 
[[Category:How to]]
 
[[Category:How to]]

Revision as of 19:13, 27 February 2009

Timing an IO computation.

import Text.Printf
import Control.Exception
import System.CPUTime
 
time :: IO t -> IO t
time a = do
    start <- getCPUTime
    v <- a
    end   <- getCPUTime
    let diff = (fromIntegral (end - start)) / (10^12)
    printf "Computation time: %0.3f sec\n" (diff :: Double)
    return v
 
main = do
    putStrLn "Starting..."
    time $ product [1..10000] `seq` return ()
    putStrLn "Done."

And running this.

$ runhaskell A.hs
Starting...
Computation time: 1.141 sec
Done.

See also Timing out computations.

Timing a pure computation:

import Text.Printf
import Control.Exception
import System.CPUTime
import Control.Parallel.Strategies
import Control.Monad
import System.Environment
 
lim :: Int
lim = 10^6
 
time :: (Num t, NFData t) => t -> IO ()
time y = do
    start <- getCPUTime
    replicateM_ lim $ do
        x <- evaluate $ 1 + y
        rnf x `seq` return ()
    end   <- getCPUTime
    let diff = (fromIntegral (end - start)) / (10^12)
    printf "Computation time: %0.9f sec\n" (diff :: Double)
    printf "Individual time: %0.9f sec\n" (diff / fromIntegral lim :: Double)
    return ()
 
main = do
    [n] <- getArgs
    let y = read n
    putStrLn "Starting..."
    time (y :: Int)
    putStrLn "Done."