Writing a Python interpreter from scratch, in half an hour.
2023-07-19 , PyCharm (Forum Hall)

You use the Python interpreter every single day. It does a lot of things for you: checks that your code has valid syntax and is properly indented, imports modules from various locations, and runs your code instruction-by-instruction.

But if you've ever wondered how exactly it happens, this talk will teach you the entire process, by building a working python interpreter from scratch.


The plan is to write a really simple, but working Python interpreter that can run Python code, from scratch.

The topics we'll be going through to build this interpreter:
- Lexing an indentation based language
- Why Indent and Dedent need to be tokens
- Writing a Recursive Descent parser
- Parsing literals: ints, strings, lists, dictionaries
- Parsing expressions
- Parsing function calls - print("Hello world!")
- Semantic analysis: removing invalid code
- A tree-walk interpreter
- Interpreting print() statements
- Running import statements
- File I/O: implementing open() calls
- Running json.loads() and json.dumps() from scratch


Expected audience expertise:

intermediate