;; ugen -> bool
(define unipolar?
  (lambda (u)
    (if (mce? u)
	(all unipolar? (mce-channels u))
	(member (ugen-name u)
		(list "Dust"
		      "Impulse" 
		      "LFPulse" 
		      "TPulse" 
		      "Trig1")))))

;; ugen -> ugen -> ugen -> ugen
(define range
  (lambda (u l r)
    (if (unipolar? u)
	(lin-lin u 0 1 l r)
	(lin-lin u -1 1 l r))))

;; ugen -> ugen -> ugen -> ugen
(define exp-range
  (lambda (u l r)
    (if (unipolar? u)
	(lin-exp u 0 1 l r)
	(lin-exp u -1 1 l r))))