C vs Python vs Ruby vs Haskell（無意味な処理deベンチマーク）

http://d.hatena.ne.jp/nshinchan01/20121114/1352907064

Haskellはそんなに遅くないよ(´･_･`)！

元のコード

mylist :: Int -> [[Int]]
mylist n = take n $ iterate (map (+n)) [1..n]

main :: IO ()
main = print.last.last $ map reverse $ mylist 4000

$ ghc -O2 muda.hs && time ./muda
15996001

real    0m2.164s
user    0m1.912s
sys     0m0.248s

ちょっと賢く

mylist :: Int -> [[Int]]
mylist n = take n $ map (take n) $ iterate (drop n) [1..n^2]

main :: IO ()
main = print.last.last $ map reverse $ mylist 4000

$ ghc -O2 muda.hs && time ./muda
[1 of 1] Compiling Main             ( muda.hs, muda.o )
Linking muda ...
15996001

real    0m0.565s
user    0m0.556s
sys     0m0.004s

Haskellの本気

mylist :: Int -> [[Int]]
mylist n =
  [ take n [ i * n + 1 .. ]
  | i <- [0 .. n - 1]
  ]

main :: IO ()
main = print.last.last $ map reverse $ mylist 4000

$ ghc -O2 muda.hs && time ./muda
[1 of 1] Compiling Main             ( muda.hs, muda.o )
Linking muda ...
15996001

real    0m0.002s
user    0m0.000s
sys     0m0.000s