Recap and Feedback

In this part, you took the first steps towards understanding the theory of programming languages. You learned of concepts like parse tree and abstract syntax tree, and how abstract syntax trees can be helpful when evaluating programs. You also learned about the theory of programming languages, including how to describe programming languages using inference rules, formation rules, and evaluation rules. In addition, you learned the basics of type systems and type checking, and took steps towards building a parser combinator that can parse a simple Lisp-like language.