Following Lennart Augustsson's improvements of the Haskell implementations of my ray tracer language comparison: http://augustss.blogspot.com/2007/11/benchmarking-ray-tracing-haskell-vs.htm... I thought I'd share the performance improvements offered by Lennart's new code with the latest release of GHC. Time in seconds to run the five versions on my Athlon64 X2 2.2GHz running 64-bit Debian Lenny: ghc-6.6.1 22.0715339184 16.5431628227 13.3524830341 11.1260569096 6.33169198036 ghc-6.8.1 16.654654026 12.3998670578 7.8039829731 7.31486296654 6.03285193443 So 6.8 is up to a third faster! The fastest implementations in other language run at around 4s, so Haskell has gone from being 3x slower in the previous implementations with GHC 6.6 to only 50% slower with the new implementations and new GHC. -- Dr Jon D Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/products/?e