# Finding primes using a primes map with Haskell and Hugs98

**George Russell
**
[email protected]

*Wed, 20 Dec 2000 15:12:46 +0100*

There are numerous ways of optimising sieving for primes, none of which have much
to do with this list. For example, two suggestions:
(1) for each k modulo 2*3*5*7, if k is divisible by 2/3/5 or 7, ignore, otherwise
sieve separately for this k on higher primes. (Or you might use products of
more or less primes, depending on memory and how high you were going.)
(2) use bitwise arithmetic.
If you look in the literature I think you'll find plenty more possibilities.
I don't really see why any of this has anything to do with Haskell though.
When it comes to seriously icky bit-twiddling algorithms I don't think Haskell
has much to offer over C, especially as you'd have to make everything unboxed if
you want comparable speed.