I recently came across a site that made coming up with regular expressions much, much easier for me: <a href="http://www.debuggex.com/">http://www.debuggex.com/</a><div> </div><div>Hopefully that will help with your "regex hell" problem. On Thursday, July 18, 2013, Greg Hendershott wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">To add to what Carl and Robby said: On Thu, Jul 18, 2013 at 2:29 AM, <<a href="javascript:;" onclick="_e(event, 'cvml', 'm0nastic@tengulabs.com')">m0nastic@tengulabs.com</a>> wrote: > (although truth be told, mail headers are surprisingly nonstandard even > within a single message) That's where net/head could definitely help. (Especially for SMTP headers, which tend to be more "interesting" than typical HTTP headers.) > I eventually discovered that I could sort of cheat, by just wrapping the > regexp-match function with a car (which worked, because this particular > list only had one element), and then it was usable from then on (and > validated true from "string?"). It's worth walking through what Carl described. Actually you're lucky, you have a specific example of something you want to do, which touches on a few basic aspects of Racket. Having said that, one pattern I've settled into using with regexps is to use `match`, which makes it convenient to "de-structure" the list. For example: (match "From: Me" [(pregexp "^(.+):\\s*(.+)$" (list all key val)) (displayln all) ; From: Me (displayln key) ; From (displayln val)]) ; Me If you don't need the "all" part, you can supply _ like so: (match "From: Me" [(pregexp "^(.+):\\s*(.+)$" (list _ key val)) (displayln key) (displayln val)]) Which is the pattern I use a lot. Again, you probably want to use net/head to deal with the gory details of SMTP headers as Robby suggested, and it would definitely be good to walk through the explorations Carl described. ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div>