Example 1. The line pattern.

(define pat1 (new line :of '(a b c d)))

(next pat1 12)
⇒ (a b c d d d d d d d d d)

(define pat1 (new line :of `(a b c ,(new random :of '(d e)))))

(next pat1 12)
⇒ (a b c e e d e d e d d d)

Example 2. Metric figures using line.

(define pat1
  (new heap :of (list (new line :rhythms 's 
                           :for (new random :of '(4 6 8)))
                      (new line :rhythms 'e :for 
                           :for (new random :of '(2 3)))
                      (new line :rhythms 'q :for 1))))

(define (play-pat reps pat lb ub)
  (process repeat reps
           for r = (* (next pat) .5)
           output (new midi :time (now)
                       :keynum (between lb ub)
                       :duration (* r 2.5))
           wait r))
                 
(events (play-pat 40 pat1 40 80) "test.mid")
⇒ "test.mid"