10 Feb
2007
10 Feb
'07
4:19 p.m.
Hello Creighton, Sunday, February 11, 2007, 12:02:09 AM, you wrote:
import Data.List primes = 2:(foldr (\x y -> if isPrime x then x:y else y) [] [3..]) where isPrime x = foldl' (\z y -> z && (if x `mod` y == 0 then False else True)) True (take (floor $ sqrt $ fromIntegral x) primes)
my program was: primes = 2:filter is_prime [3,5..] is_prime n = all (\p-> n `mod` p /= 0) (takeWhile (\p-> p*p<=n) primes) it's faster to calculate square instead of square root. also note that (if x `mod` y == 0 then False else True) can be replaced with (x `mod` y /= 0) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com