[tosh]

love this on keyword parameters:

> Rtml even depended heavily on keyword parameters, which up to that time I had always considered one of the more dubious features of Common Lisp. Because of the way Web-based software gets released, you have to design the software so that it's easy to change. And Rtml itself had to be easy to change, just like any other part of the software. Most of the operators in Rtml were designed to take keyword parameters, and what a help that turned out to be. If I wanted to add another dimension to the behavior of one of the operators, I could just add a new keyword parameter, and everyone's existing templates would continue to work. A few of the Rtml operators didn't take keyword parameters, because I didn't think I'd ever need to change them, and almost every one I ended up kicking myself about later. If I could go back and start over from scratch, one of the things I'd change would be that I'd make every Rtml operator take keyword parameters.