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've learned a reasonable amount of ML at uni but Haskell is the first lazy language I've used.. I think the inefficiency is possibly due to the laziness but I'm not positive. I'd love if someone could show me how to do this in Haskell somewhere near as fast as C - at the moment I have a C version which runs in about a tenth of a second ( http://github.com/malcster/project-euler-solutions--c-/tree/master/10.c ). My haskell attempts are http://github.com/malcster/project-euler-solutions/tree/master/10better.hs (using the sieve) and http://github.com/malcster/project-euler-solutions/tree/master/10.hs (using possibly an even worse method, but seems to be a bit faster). If anyone could point out any neat strictness annotations or anything else I could put in, that would be cool. Cheers, Malcolm