[Haskell-cafe] nbody (my own attempt) and performance problems

I thought it would be a nice exercise (and a good learning experience) to try and solve the nbody problem from the debian language shootout. Unfortunately, my code sucks. There is a massive space leak and performance is even worse. On the bright side, my implementation is purely functional. My twist: I manually unrolled a few loops from the C++ version. I believe that most of my performance problems stem from my abuse of tuple. The bodies are passed as a tuple of planets, a planet is a tuple of (position, velocity, mass) and the vectors position and velocity are also tuples of type double. My lame justification for that is to make it nice and handy to pass data around. Any tips would be greatly appreciated. --ryan