In the previous program, you used both integer and string data and never had to tell the Scheme language what type of data was being used. 在先前的程序中,您使用了整型和字符串数据,因此没有告诉Scheme语言正在使用的是哪种类型的数据。
Types system and correctness of types system. Types system is part of program language. It follow the tracks type of the variables including types of expressions. 类型与类型系统的正确性:类型系统是算法语言的一个组成部分,它监视程序中变量的类型,包括所有表达式的类型;
The main feature of the system is: It provides a uniform language; the program of that language can access multi-views of program ( AST, class graph, type etc.). 该系统的特征是:提供一个可扩展的基础语言,允许该语言的程序访问程序的多个视图(如AST、类图、类型、上下文等)。