These files implement a very simple facility for finding out a "high-water mark" in the amount of memory your GHC-Haskell program is using. It only counts memory managed by GHC's storage manager, so, as Simon Marlow says: Note that this only counts memory allocated by the GHC storage manager; it doesn't include the data segments, malloc(), the C stack, or other mmap()'d stuff. Be careful if your program is using any of these other allocation methods (perhaps via an external library through the FFI). The file Main.hs is provided here as an example, to compile it, use: ghc HighWaterMark.hs mblocks.c Main.hs Cheers, Bernie Pope.