Exercise 3.34 · 习题

Exercise 3.34: Louis Reasoner wants to build a
squarer, a constraint device with two terminals such that the value of
connector b on the second terminal will always be the square of the
value a on the first terminal. He proposes the following simple device
made from a multiplier:

(define (squarer a b) (multiplier a a b))

There is a serious flaw in this idea. Explain.

练习 3.34：Louis Reasoner 想构建一个平方器，这是一种带两个端口的约束器件，使得第二个端口上的连接器 b 的值始终等于第一个端口上的值 a 的平方。他提出了以下由乘法器构成的简单器件：

(define (squarer a b) (multiplier a a b))

这个想法存在一个严重的缺陷。请加以解释。