;; returns a pc-set based on a list of intervals
;; plst is the seed for the progression
;; usually this will be a list with one element
(define pc:from-intervals
(lambda (plst intervals)
(if (null? intervals)
(reverse plst)
(pc:from-intervals (cons (modulo (+ (car plst)
(car intervals))
12)
plst)
(cdr intervals)))))