dons:
hughperkins:
Hey, I just realized I can shave off another 30% in C# ;-) So now the timings become:
Ok. So do the same thing to the Haskell program. The compilers should produce pretty much identical assembly.
Oh, and I forgot you count up by two now. Here's the Haskell transliteration (again). {-# OPTIONS -O2 -optc-O -fbang-patterns #-} import Control.Monad.ST import Data.Array.ST import Data.Array.Base import System import Control.Monad import Data.Bits main = print (pureSieve 10000000) pureSieve :: Int -> Int pureSieve n = runST( sieve n ) sieve n = do a <- newArray (3,n) True :: ST s (STUArray s Int Bool) let cutoff = truncate (sqrt (fromIntegral n)) + 1 go a n cutoff 3 1 go !a !m cutoff !n !c | n >= m = return c | otherwise = do e <- unsafeRead a n if e then if n < cutoff then let loop !j | j < m = do x <- unsafeRead a j when x $ unsafeWrite a j False loop (j+n) | otherwise = go a m cutoff (n+2) (c+1) in loop ( if n < 46340 then n * n else n `shiftL` 1) else go a m cutoff (n+2) (c+1) else go a m cutoff (n+2) c Marginally faster: $ time ./primes 664579 ./primes 0.34s user 0.00s system 89% cpu 0.385 total Very cache-dependent though, so widely varying runtimes could be expected. -- Don