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)