anchor.diff:  (defparameter *and-gate-delay* 3)
   (defparameter *or-gate-delay* 5)
   (defvar the-agenda (make-agenda))
  +(setq the-agenda (make-agenda))
   ;;;定义一个监测器
   (defun probe (name wire)
     (add-action! wire
  
positive.code:   (cond ((or (= s1 1) (= s2 1)) 1)
  	(t 0)))
  ;;;;3.29
  (defun or-gate (a1 a2 output)
    (let ((na1 (make-wire))
  	(na2 (make-wire))
  	(na1a2 (make-wire)))
  
negative.code:   (propagate)
    (set-signal! input-2 1)
    (propagate))
  
  ;;;电路设计只是一个例子，其中的设计思路是值得思考的。好好想一想，在大脑里模拟整个程序的运行过程。
  
  ;;;;约束的传播
  
  (defvar *C* (make-connector))
  (defvar *F* (make-connector))
  (celsius-fahrenheit-converter *C* *F*)
  
  (defun celsisus-fahrenheit-converter (*C* *F*)
    (let ((u (make-connector))
  	(v (make-connector))
  	(w (make-connector))
  	(x (make-connector))
  	(y (make-connector)))
      (multiplier c w u)
      (multiplier v x u)
      (adder v y f)
      (constant 9 w)
      (constant 5 x)
      (constant 32 y)
      'ok))
  
  