Hi, Yesterday evening I had a go at porting Bob Jenkins' hash function (http://www.burtleburtle.net/bob/c/lookup3.c) to Haskell. The first version I came up with ran 20 times slower than C. Thanks to Don Stewart's suggestions on IRC, I managed to improve the performance by replacing tuples with a strict type so the current version is about 10 times slower than C code. Is there any way this can be further optimized? To keep things fair I've simplified the C function so it works on one byte at a time as opposed to an int at a time. The code was compiled with GHC-6.6 on a G5 iMac running OS X 10.4. Options used to compile the version using the hash function written in Haskell: ghc -O -funbox-strict-fields -fglasgow-exts -fbang-patterns -cpp -o test hashByteString.hs test.hs Options used to compile the version using the hash function in C: ghc -O -fglasgow-exts -ffi -fbang-patterns -cpp -DCHASH -o ctest ctest.c test.hs Ivan Tomac