Exercise 4.3 · 习题

Exercise 4.3: Rewrite eval so that the

dispatch is done in data-directed style. Compare this with the data-directed

differentiation procedure of Exercise 2.73. (You may use the car

of a compound expression as the type of the expression, as is appropriate for

the syntax implemented in this section.)

练习 4.3：将 eval 重写为数据导向风格来完成分派。将此与练习 2.73 中的数据导向求导过程作比较。（可以将复合表达式的 car 作为表达式的类型，这与本节所实现的语法相适应。）