Simple benchmark

Boxed.hs

{-

$ ghc --make -O0 Boxed.hs 

$ time ./Boxed u 100000000
987459712

real	0m1.034s
user	0m1.028s
sys	0m0.004s

$ time ./Boxed b 100000000
987459712

real	0m2.342s
user	0m2.320s
sys	0m0.020s

With -O1 and higher the times are the same.

-}

{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE MagicHash #-}

module Main where

import GHC.Base
import System.Environment (getArgs)


unboxed :: Int -> Int
unboxed n = I# $ myAdd [1..n] 0#

myAdd :: [Int] -> Int# -> Int#
myAdd []         a = a
myAdd (I# x: xs) a = myAdd xs (x +# a)


boxed :: Int -> Int
boxed n = myAddB [1..n] 0

myAddB :: [Int] -> Int -> Int
myAddB []      a = a
myAddB (x:xs) !a = myAddB xs (x + a)


getFun :: String -> (Int -> Int)
getFun "b" = boxed
getFun "u" = unboxed


main :: IO ()
main = do
  args <- getArgs
  case args of
    (fun:arg:_) -> print $ (getFun fun) (read arg)
    _           -> putStrLn "Wrong arguments"