I'm in a profiling kind of mood (read: am sick of my program taking too long to run), but when I ghc with -prof -auto-all (or -auto or whatever), when I try to run my program it seg faults. I don't want to attach all the code, since it's really long, but I *have* tested profiling on smaller programs and it works fine. (Note that the program crashes regardless of whether I put +RTS -p or not.) Here are some "unusual" things I'm doing; hopefully someone will be able to say "oh, there's your problem": - using the ghc binary package (which using FastMutInt -- I don't really know what this does, but it looks scary) - i'm only compiling the main program with profiling -- it imports a whole lot of modules which are compiled with -O2, including binary which is compiled using -cpp also - i use the Word8 type extensively - i use unsafePerformIO (but only once per run of the code) - i use UArray Int Double (i think this also uses upIO) - uhm...i do a lot of file io :) That's all I can think of at the moment. It dies regarless of whether I use -O, -O2, or neither... -- Hal Daume III "Computer science is no more about computers | hdaume@isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume