Will Ness <will_n48 <at> yahoo.com> writes:

> primes   = 2: 3: sieve 0 primes' 5
> primes'  = tail primes
> sieve k (p:ps) x
>          = [x | x <- [x,x+2..p*p-2],
>                  and [(x`rem`p)/=0 | p <- take k primes']]
>            ++ sieve (k+1) ps (p*p+2)
>
> (thanks to Leon P.Smith for his brilliant idea of directly generating
> the spans of odds instead of calling 'span' on the infinite odds list).
>

> The relative performance vs the PQ-version is:
>
>   100,000   300,000   1,000,000  primes produced
>    0.6       0.75      0.97
>

One _crucial_ tidbit I've left out: _type_signature_.

Adding (:: [Int]) speeds this code up more than TWICE!

:) :)