(define (gen-condition expr pattern)
"Helper function for `with-music-match'.
Generate an form that checks if the properties of `expr'
-match thoses desscribed in `pattern'."
+match thoses described in `pattern'."
(let* (;; all (property . value) found at the first depth in pattern,
;; including a (name . <Musictype>) pair.
(pat-all-props (cons (cons 'name (second pattern))