On Sun, Nov 23, 2008 at 5:28 PM, Malcolm Reynolds
Hello all,
I'm attempting to learn Haskell by going through the project euler problems. Number 10, http://projecteuler.net/index.php?section=problems&id=10 , involves summing prime numbers. It's easy in terms of coding something up that works, but I'm having a lot of trouble getting decent performance.
I realize that these early prime number related Euler problems are about writing your own efficient prime generator, so you may want to ignore this message for now. But later on when the problems just happen to involve primes, but the generator is kind of assumed, you may want to check out this collection: http://www.cs.hmc.edu/~oneill/code/haskell-primes.zip The file "ONeillPrimes.hs" contains what is, I think, generally considered to be one of the fastest pure-Haskell prime generators. In particular, this program:
import ONeillPrimes ( primesToLimit )
main = ( print . sum . primesToLimit ) 2000000
Gives the correct answer on my machine in about 0.3 seconds.