Python Interpreter / Transpiler in OCaml

In order to learn OCaml (and more of Python), I chose this as my project. Still WIP. Lexes, parses, and evaluates a subset of Python including arithmetic, variables, lists, dicts, functions, and basic stdlib. It also supports higher-order functions and lazily evaluates expressions. Currently pass-by-copy, without references for data structures. To get a feel of what it can interpret, have a look at example.py.

Useage

To build, run:

dune build

To run a Python file, run:

dune exec python-interpreter test.py

If no arguments are provided, the interpreter will read from stdin:

cat test.py | dune exec python-interpreter

You can also directly invoke the generated binary in _build/install/default/bin/python-interpreter.

To run tests, run:

dune runtest

Tests use ppx_expect inline expect tests. Test files live in test/.

Architecture

The interpreter pipeline: Source → Lexer (ocamllex) → Parser (menhir) → AST → Evaluator.
The lexer and parser are generated by ocamllex and menhir respectively.

Implemented types

• int, float, str, bool, None
• list, dict

Implemented statements

• assignment, function definition, sole expression
• if, elif, else
• for, while
• pass, return

Implemented Built-in Functions

• print, input
• range, len
• int, float, bool, str, list
• binary operators: +, -, *, /, %, ==, !=, >, <, >=, <=, and, or, in, not not in
• list and dictionary access: x[i], x[i]=y
• list and string slicing: x[i:j], x[i:j:k], etc.
• math utils: abs, pow, sqrt, min, max, sum