Chasing down my memory leak I got into a weird situation where adding a magic manual SCC section and compiling with -prof makes the leak disappear. Now, I'll take any solution I can find - but this black voodoo only works for the short program I created for investigating the leak. It fails on the real program. Probably not enough fingernails in the voodoo doll or something :-( The code is in http://hpaste.org/1314#a1 if anyone at all is willing to take pity on me and explain what I'm doing wrong. This is the second system I tried writing in Haskell, and in both cases I hit a brick wall due to uncontrollable memory consumption. I'm just about ready to give up on Haskell as a practical language for non-trivial tasks. I can achieve the results I want in very short, elegant code... and as such it will have a place in my toolbox for various small tasks... but I lack the deep lore required to make it behave well for "large" inputs. At this point I have to take it on faith that it is even possible to do so in the first place :-(