Exercise 2.83 · 习题

Exercise 2.83: Suppose you are designing a

generic arithmetic system for dealing with the tower of types shown in

Figure 2.25: integer, rational, real, complex. For each type (except

complex), design a procedure that raises objects of that type one level in the

tower. Show how to install a generic raise operation that will work for

each type (except complex).

练习 2.83：假设你正在设计一个通用算术系统，用于处理图 2.25 所示的类型塔：integer（整数）、rational（有理数）、real（实数）、complex（复数）。对每种类型（complex 除外），设计一个过程，将该类型的对象在塔中提升一个层次。说明如何安装一个通用的 raise 操作，使其适用于每种类型（complex 除外）。