Fomus

(let ((c1 (fomus
           :output :chunk
           :global (list (make-timesig :off 0 :time '(5 8)))
           :auto-cautionary-accs t
           :parts
           (list
            (make-part
             :partid 'hp                ; identical ids are matched
             :name "Harpsichord"
             :instr :harpsichord
             :events
             (loop
               for off from 0 to 8 by 1/2
               collect (make-note :off off
                                  :dur (if (< off 8) 1/2 1)
                                  :note (+ 48 (random 25))))))))
      (c2 (fomus
           :output :chunk
           :global (list (make-timesig :off 0 :time '(5 8)))
           :auto-cautionary-accs t
           :parts
           (list
            (make-part
             :partid 'hp
             :name "Harpsichord"
             :instr :harpsichord
             :events
             (loop
               for off from 10 to 16 by 1/2
               collect (make-note :off off
                                  :dur (if (< off 16) 1/2 1)
                                  :note (+ 48 (random 25)))))))))
  (fomus (list c1 c2)
         :output '(:lilypond :view t)))