Since Björn Bringert suggested (on IRC) the problem could be due to laziness, and that I should force the result string before giving it to "output", I've been playing around a bit. (The program is somewhat more involved than the short test I provided earlier, but available on request). Without strictness, I get a blank page, and an message in the error_log: [Thu May 22 22:00:15 2008] [error] [client 10.1.4.222] snp.cgi: Prelude.last: empty list, referer: http://gadidae/snp.c gi This is okay, but I would still like some output to the user. With strict evaluation of output's argument, I instead get a web page that appears to hang (showing a hourglass cursor and animated toolbar icon). In the log, I find: [Thu May 22 22:22:44 2008] [error] [client 10.1.4.222] Premature end of script headers: snp-strict.cgi, referer: http://gadidae/snp-strict.cgi [Thu May 22 22:26:32 2008] [error] [client 10.1.4.222] Premature end of script headers: snp-strict.cgi, referer: http://gadidae/snp-strict.cgi [Thu May 22 22:27:44 2008] [error] [client 10.1.4.222] (500,"Internal Server Error",["Prelude.last: empty list"]), referer: http://gadidae/snp-strict.cgi [Thu May 22 22:31:32 2008] [error] [client 10.1.4.222] (500,"Internal Server Error",["Prelude.last: empty list"]), referer: http://gadidae/snp-strict.cgi I interpret this as the system putting things on hold for about ten minutes before terminating my script, and for some reason, the intended error document is put in the log instead of being returned to the browser/client. This is just weird. (I do actually get a 500 from the server, but that just talks about "premature end of script headers", and not about the actual bug in my program, so I belive this is just what apache says when terminating a runaway cgi) Network.CGI does look like an established library, certainly the documentation I find is very good and complete, and the interface is concise, logical, and to the point. It seems a shame that it doesn't work. Does anybody else have it working? I'd be very happy to hear about it, even if it just works for you. -k -- If I haven't seen further, it is by standing in the footprints of giants