common-lisp
There are plenty of Lisp Markup Languages out there - every Lisp
programmer seems to write at least one during his career - and CL-WHO
(where WHO means "with-html-output" for want of a better acronym) is
probably just as good or bad as the next one. They are all more or
less similar in that they provide convenient means to convert
S-expressions intermingled with code into (X)HTML, XML, or whatever
but differ with respect to syntax, implementation, and
API.