Results

Programming_Misc/Haskell/integral  » cabal exec runhaskell Main.hs
benchmarking integral/mine
time                 49.60 ns   (48.52 ns .. 50.70 ns)
                     0.996 R²   (0.994 R² .. 0.998 R²)
mean                 50.25 ns   (49.22 ns .. 51.44 ns)
std dev              3.635 ns   (2.956 ns .. 4.986 ns)
variance introduced by outliers: 85% (severely inflated)

benchmarking integral/not mine
time                 50.62 ns   (49.77 ns .. 51.62 ns)
                     0.998 R²   (0.997 R² .. 0.999 R²)
mean                 50.80 ns   (50.06 ns .. 51.50 ns)
std dev              2.398 ns   (1.971 ns .. 2.999 ns)
variance introduced by outliers: 69% (severely inflated)

Source

module Main where

import           Criterion.Main
import qualified Data.ByteString.Lazy       as DBSL
import qualified Data.ByteString.Lazy.Char8 as DBSLC
import qualified Text.Show.ByteString       as TSBS

isIntegral :: Float -> Bool
isIntegral = DBSL.isSuffixOf (DBSLC.pack ".0") . TSBS.show

isIntegral' :: Float -> Bool
isIntegral' x = x == fromInteger (round x)

mapII :: [Float] -> [Bool]
mapII = map isIntegral

mapII' :: [Float] -> [Bool]
mapII' = map isIntegral'

lotsOfFloats :: [Float]
lotsOfFloats = map (/ 100) [1..10000]

main :: IO ()
main = defaultMain [
  bgroup "integral" [ bench "mine"      $ whnf mapII lotsOfFloats
                    , bench "not mine"  $ whnf mapII' lotsOfFloats
                    ]
  ]