Chapter 8

1. Regular languages are ones that can be defined by a regular expression, which is a combination of three operators: concatenation, alternation, and repetition. Context-free languages are ones that can contain regular operators, plus matching symbols (such as parentheses). Context-dependent languages are those in which the validity of any expression may depend on any other expression defined previously.
2. It is a set of rules in which the program is a symbol, and every symbol is defined as the concatenation or alternation of symbols or characters.
3. It is a program that gets as input a formal definition of a programming language and generates as output a compiler, which is a program that parses (or even compiles to machine language) programs written in the language specified by that formal definition.
4. It is a function that takes as input one or more parsers and returns a parser that combines the input parsers in some way.
5. Because, before the 2018 edition of Rust, the Rust language...