On Fri, Mar 26, 2010 at 10:46 AM, Rafael Cunha de Almeida < almeida...@gmail.com> wrote:
> Hello, > > During a talk with a friend I came up with two programs, one written in > C and another in haskell. > > Haskell > main :: IO () > main = print $ rangeI 0 0 > > rangeK :: Int -> Int -> Int -> Int -> Int > rangeK i j k acc > | k < 1000 = > if i * i + j * j + k * k `mod` 7 == 0 > then rangeK i j (k+1) (acc+1) > else rangeK i j (k+1) acc > | otherwise = acc > > rangeJ :: Int -> Int -> Int -> Int > rangeJ i j acc > | j < 1000 = rangeJ i (j+1) (acc + rangeK i j 0 0) > | otherwise = acc > > rangeI :: Int -> Int -> Int > rangeI i acc > | i < 1000 = rangeI (i+1) (acc + (rangeJ i 0 0)) > | otherwise = acc > You might try using bang patterns. It's possible that GHC didn't detect the strictness. Only way I know to check is to look at the core. Use something like ghc-core from Hackage to view it. Ideally the core is using Int# instead of Int and avoiding lots of boxing. > I compiled the haskell code with ghc -O3 and I compiled the C code with > gcc -O3. The execution time of the programs were dramatically different. > You can test it yourselves, but here is the time I've got in my system: > You might try -Odph . See http://book.realworldhaskell.org/read/profiling-and-optimization.htmlfor more ideas. Jason
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
