# Timing computations

### From HaskellWiki

(Difference between revisions)

DonStewart (Talk | contribs) (category) |
DonStewart (Talk | contribs) |
||

(3 intermediate revisions by one user not shown) | |||

Line 1: | Line 1: | ||

− | Timing an IO computation. |
+ | Timing an IO computation -- very basic approach. For a full featured, statistically sound benchmarking system, see the [http://hackage.haskell.org/package/criterion criterion] package. |

<haskell> |
<haskell> |
||

Line 30: | Line 30: | ||

</haskell> |
</haskell> |
||

− | See also [[Timing out computations]]. |
+ | See also [[Timing out computations]] and [[Timing computation in cycles]]. |

+ | |||

+ | Timing a pure computation: |
||

+ | |||

+ | <haskell> |
||

+ | 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." |
||

+ | </haskell> |
||

[[Category:Code]] |
[[Category:Code]] |
||

[[Category:Idioms]] |
[[Category:Idioms]] |
||

+ | [[Category:How to]] |

## Latest revision as of 03:14, 27 January 2010

Timing an IO computation -- very basic approach. For a full featured, statistically sound benchmarking system, see the criterion package.

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 and Timing computation in cycles.

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."