Although uri-template does not implement the operators introduced in the 02 and later drafts of the URI Template standard, it does allow arbitrary Lisp expressions in template placeholders, which gives simpler and more powerful templates.
Examples use:
Template interpolation:
(let ((foo 1))
https://www.example.com/widget/{foo}/parts)
=> "https://www.example.com/widget/1/parts"
Template destructuring:
(uri-template-bind (#Uhttps://www.example.com/{part}/{number})
"https://www.example.com/widget/1"
(list part (parse-integer number) %uri-host))
=> ("widget" 1 "www.example.com")
License: LGPL-3.0-or-later
Homepage: https://common-lisp.net/project/uri-template/
Source repository: https://gitlab.common-lisp.net/uri-template/uri-template.git
Mailing list: uri-template-devel@common-lisp.net
Author: Vladimir Sedach
Related projects: puri (URI parsing and representation) cl-uri-templates (fork of uri-template supporting operators)