HTML-TEMPLATE is a portable library for Common Lisp which can be used to fill templates with arbitrary (string) values at runtime. (Actually, it doesn't matter whether the result is HTML. It's just very likely that this will be what the library is mostly used for.)
It is loosely modeled after the Perl module HTML::Template and partially compatible with a its syntax, though both libraries contain some extensions that the other does not support.
HTML-TEMPLATE translates templates into efficient closures which can be re-used as often as needed. It uses an intelligent cache mechanism so you can nevertheless update templates while your program is running and have the changes take effect immediately.
Complete documentation for HTML-TEMPLATE can be found in the docs
directory or at the project documentation
site.