This is a port of the sample 2D physics program that was provided along with Chris Hecker's excellent physics articles. The sample code Hecker provided was written in C++. I ported it to Haskell as a learning exercise in both Haskell and physics simulations. I hope that the Haskell port is true to the original in terms of behavior.
This distribution includes the physics2d binary, which is a PPC
executable for Mac OS X. Any other system with the Glasgow Haskell
Compiler should also be able to produce a binary. On Mac OS X,
physics2d uses X11.app for its display.
Here is the source code: physics2d-0.1.2.tgz
Here is the darcs repository, from which you can also browse the source code: physics2d
It currently only compiles without issue under Mac OS X, but I'm sure it would just be a matter of mucking with the Makefile to make it compile under Linux and even Windows.