;; package xyz
(defun rr/prop-access (ast parse-fn)
  (unless (symbolp (cadr ast))
    (error "invalid - property access (@ ...) form *must* start with a symbol"))
  (let ((xyz (reduce (lambda (acc e)
                       (if (symbolp e)
                           (cons e acc)
                           (list `(prop-get ,(cons 'prop (reverse acc)) ,(funcall parse-fn e))))) (cdr ast) :initial-value '())))
    (if (eq (car xyz) 'prop-get)
        xyz
        `(prop ,@(reverse xyz)))))

;; only for reference
(defun rewrite-ast (ast ruleset)
  "parse AST, applying rewrite ruleset"
  (labels ((rewrite-ast* (ast)
           (cond ((atom ast) ast)
                 ((symbolp (car ast))
                  (let ((rewrite-rule (getf ruleset (car ast))))
                    (if rewrite-rule
                        (funcall rewrite-rule ast #'rewrite-ast*)
                        (mapcar #'rewrite-ast* ast))))
                 (t (mapcar #'rewrite-ast* ast)))))
    (rewrite-ast* ast)))


;; from another package, xyz/tests, I get:
;; (xyz::prop ...)
;; from (rewrite-ast '(@ foo bar) '(@ rr/prop-access))
;; => (XYZ::PROP FOO BAR)