Fomus

(defparameter *part* (new fms:part :instr '(:piano :simultlim 1) :partid 'pno))

(defun polygen (voice len minp maxp)
  (process repeat len
    output (new fms:note
             :off (now)
             :voice voice
             :partid 'pno
             :note (between minp maxp)
             :dur 1/2)
    wait 1/2))

(events (list (polygen '(1 2) 20 50 80) (polygen '(1 2) 20 40 70)) "/tmp/fomus.ly" :parts *part* :view t)