I have a Word64 -> Bool function called only012 that returns True iff the digits in base 10 are 0, 1 or 2.

I wand to make sure that I'm competitive with C, so I wrote the following code:

Haskell version:

C version:

http://lpaste.net/100128

$ ghc --make -O3 303only012.hs && time ./303only012 50000000 > /dev/null

./303only012 50000000 > /dev/null  21.44s user 0.41s system 91% cpu 23.754 total

$ g++ -O3 303only012.cpp -o 303cpponly012 && time ./303cpponly012 50000000 > /dev/null

./303cpponly012 50000000 > /dev/null  13.87s user 0.03s system 95% cpu 14.577 total

So there's a difference, but I'm not sure if it's related to my algorithm or related to IO/RTS.

The core output of only012 looks quite tight: http://lpaste.net/100130

Am I doing the IO part right, that is fast IO that is not screwing my benckmark? I'm not so sure about that since I use a convoluted way to print the boolean result in Haskell.

Cheers,