[Haskell-cafe] how to measure memory usage?

How could I measure the amount of memory that my ghc-compiled program is actually using, from inside the program? It is expanding nodes in a (game) tree, and I need to stop this when it gets near the physical limits of the system (or some other limit that I want to set on the command line) The node size is varying so I cannot just pre-compute a maximal number of nodes. Thanks - J.W. PS: the program is this: http://www.littlegolem.net/jsp/info/player.jsp?plid=22146