I want to build my own version of TypeScript, mainly focusing on the type checker. I do not yet have much background in compilers, and I was hoping to study the Go implementation line by line before making my own modified version. However, the repository has many directories and files with unfamiliar names, so I am not sure where to begin or how to trace the overall structure. What is a sensible starting point, and how can I learn to navigate and understand a codebase this large?
3 Answers
An AI coding assistant can be useful for orientation if you treat it as a guide rather than a replacement for reading. Give it the repository structure and ask it to explain the purpose of a package, identify the call path for type checking, or suggest a small feature to trace end to end. Verify its explanations against the source, and use tests and a debugger to confirm how the code actually behaves.
Before diving into the implementation, learn the basics of compiler construction. A resource such as Crafting Interpreters can give you a foundation in lexing, parsing, syntax trees, and interpretation. Once those concepts are familiar, the type checker will be much easier to follow. Also make sure you are studying a specific repository and version, since the layout and entry points can vary between implementations.
Look for the program's entry point and trace execution outward from there. Find the command or package that starts the compiler, then follow how it loads files, parses them, builds its intermediate representation or syntax tree, and eventually performs type checking. Reading every file line by line is usually inefficient; instead, form a map of the major stages first and inspect individual files when you know what role they play.
That makes sense. I can use it to build an initial map of the codebase, then check the suggested paths myself instead of trusting every explanation blindly.