Thanks Eli - I'll look into scheme_add_atexit_closer and exit-handler more. <div class="gmail_quote">On Mon, Mar 23, 2009 at 10:42 PM, Eli Barzilay <<a href="mailto:eli@barzilay.org">eli@barzilay.org</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">At the Scheme level `exit' will just exit the process, so dynamic wind etc do nothing. For example, (dynamic-wind void exit (lambda () (printf "bye\n"))) will not do the printout before leaving. There is a `scheme_add_atexit_closer' function in the mzscheme api, which might do what you want, for example: (require scheme/foreign) (unsafe!) ((get-ffi-obj "scheme_add_atexit_closer" #f (_fun (_fun _scheme _pointer _pointer -> _void) -> _void)) (lambda (x _1 _2) (printf "bye\n"))) but this is called for managed objects, so you might need to use some more of the C api to register your objects. (Or just do whatever you need, and make sure that there's at least one managed object that will cause your handler to be called.) If you prefer a Scheme solution, then perhaps it is better to change the exit handler: (exit-handler (let ([old (exit-handler)]) (lambda (s) (printf "bye\n") (old s)))) this will work if you do it when starting your code *and* if you always exit your program using `exit' (for example, you register an exception handler to print the error and call `exit' instead of letting it abort). But if that's what you're doing, you can just as well write your own `exit' function that will do the cleanup and then actually exit. -- ((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay: <a href="http://www.barzilay.org/" target="_blank">http://www.barzilay.org/</a> Maze is Life! </blockquote></div>