benchmarks/haskell/Timer.hs · text

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1{-# LANGUAGE BangPatterns #-}

3module Timer (timer) where

5import Control.Exception (evaluate)

6import Data.Time.Clock.POSIX (getPOSIXTime)

7import GHC.Float (FFFormat(..), formatRealFloat)

9ickyRound :: Int -> Double -> String

10ickyRound k = formatRealFloat FFFixed (Just k)

12timer :: Int -> a -> (a -> b) -> IO String

13timer count a0 f = do

14 let loop !k !fastest

15 | k <= 0 = return fastest

16 | otherwise = do

17 start <- getPOSIXTime

18 let inner a i

19 | i <= 0 = return ()

20 | otherwise = evaluate (f a) >> inner a (i-1)

21 inner a0 count

22 end <- getPOSIXTime

23 let elapsed = end - start

24 loop (k-1) (min fastest (elapsed / fromIntegral count))

25 t <- loop (3::Int) 1e300

26 let log10 x = log x / log 10

27 ft = realToFrac t

28 prec = round (log10 (fromIntegral count) - log10 ft)

29 return $! ickyRound prec ft

30{-# NOINLINE timer #-}