anchor.diff:  
   (defvar *config* nil)
   
  -(defvar *propery-names* '((:family . "family")
  +(defvar *property-names* '((:family . "family")
                             (:familylang . "familylang")
                             (:style . "style")
                             (:stylelang . "stylelang")
  
positive.code:            (fc-object-set-destroy ,object-set))))))
  
  (defun prop-to-name (prop)
    (let ((d (assoc prop *propery-names*)))
      (unless d
        (error "Unknown property: ~s" prop))
      (cdr d)))
  
negative.code: (defun pattern-to-lisp (pattern fields)
    (loop
      for field in fields
      for v = (assoc field *property-names*)
      when v
        append (let* ((name (cdr v))
                      (first-result (pattern-get-internal pattern name 0)))
  