According to RFC2616, there are GET, POST, PUT, PATCH and DELETE methods. You may register handler for specified URL rule to these methods.
There would be a HEAD method, but in GNU Artanis, the HEAD method is handled by the server, so users can not use it.
(method rule handler)
And the handler could be one of two types, depending on your needs:
(lambda () ... ret) (lambda (rc) ... ret)
ret also has two types:
(get "/hello" (lambda () "hello world"))
For POST method:
(post "/auth" (lambda (rc) ...))