- XML namespaces are similar to Common Lisp packages.
- Even uses same syntax: prefix:local-name
- However, namespace is just a URL string.
- Namespace declarations map prefix to a URL.
- Namespace declarations can be lexically nested
(hence must be done after read-time).
(define-namespace html "some-unique-string")
(html:html (html:body (html:p "Hello")))