Introduction

Why Build an Interpreter?

Understanding how programming languages work is one of the most rewarding topics in computer science. By building an interpreter from scratch, you will demystify the magic behind every language you use.

  • Lexing — break source code into tokens.
  • Parsing — transform tokens into an abstract syntax tree (AST).
  • Evaluation — walk the AST to execute programs.
  • From scratch — no libraries, no shortcuts, just you and JavaScript.

What You Will Learn

  • Tokenization and lexical analysis
  • Recursive descent parsing
  • Abstract syntax tree design
  • Tree-walking interpretation
  • Variables, expressions, and control flow
  • Functions and closures
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