전선은 게이트에 알리고 agenda는 지연을 시뮬레이션 시간으로 바꾼다.

(begin
  (define current-time 0)
  (define agenda '())
  (define (insert-event event events)
    (cond ((null? events) (list event))
          ((< (car event) (car (car events)))
           (cons event events))
          (else
           (cons (car events)
                 (insert-event event (cdr events))))))
  (define (after-delay delay action)
    (set! agenda
          (insert-event
            (list (+ current-time delay) action)
            agenda)))
  (define (propagate)
    (if (null? agenda)
        'done
        (let ((event (car agenda)))
          (set! agenda (cdr agenda))
          (set! current-time (car event))
          ((cadr event))
          (propagate))))
  (define (make-wire)
    (let ((signal 0) (actions '()))
      (define (call-each procedures)
        (if (null? procedures)
            'done
            (begin
              ((car procedures))
              (call-each (cdr procedures)))))
      (define (set-signal new-value)
        (if (= signal new-value)
            'unchanged
            (begin
              (set! signal new-value)
              (call-each actions)
              'changed)))
      (define (add-action action)
        (set! actions (cons action actions))
        (action)
        'ok)
      (lambda (message)
        (cond ((eq? message 'get) signal)
              ((eq? message 'set) set-signal)
              ((eq? message 'add-action) add-action)
              (else 'unknown-wire-message)))))
  (define (get-signal wire) (wire 'get))
  (define (set-signal! wire value) ((wire 'set) value))
  (define (add-action! wire action) ((wire 'add-action) action))
  (define (logical-not signal) (if (= signal 0) 1 0))
  (define (inverter input output)
    (define (action)
      (let ((new-value (logical-not (get-signal input))))
        (after-delay 2
          (lambda () (set-signal! output new-value)))))
    (add-action! input action)
    'ok)
  (define input (make-wire))
  (define output (make-wire))
  (inverter input output)
  (propagate)
  (define initial-time current-time)
  (define initial-output (get-signal output))
  (set-signal! input 1)
  (propagate)
  (list initial-time
        initial-output
        current-time
        (get-signal output)))