The current syntax: instead of writing
(register-groups-bind (method url version-major version-minor) ("(\\S+)\\s+(\\S+)\\s+HTTP/<!-- -->(\\d+).(\\d+)$" line) ...)write
(match-bind (method (+ (space)) url (+ (space)) "HTTP/" (version-major (integer)) "." (version-minor (integer)) (last)) line ...)Which might be clearer and doesn't involve mentioning the captured variables twice.
cl-ppcre also has a similar sexpy alternative for its regular expressions called terse-ppcre