py-lox

A tree-walking Lox interpreter in Python - based on the book "Crafting Interpreters" by Robert Nystrom

Why?

Programming language implementations are interesting!
Get better at OOP (the book uses Java already, but I don't know Java)
Get better at Python

Features

Py-lox is a fully-featured interpreter for the Lox programming language. The lox language is very similar to Java, with focus on object-oriented design.

The Lox language has the following features:

Variables (var)
Conditionals (if, else if, else)
Iteration (for, while)
Functions (fun)
Classes (class, super)
Printing (print)
Comments (//)

Running the Interpreter

Clone the repository:

git clone https://github.com/kris-gaudel/py-lox.git

Run the interpreter

cd py-lox
cd pylox
cd src

To run the REPL:

python3 lox.py

To run a Lox file:

python3 lox.py [path to file]

Examples

Printing to output:

print "Hello, world!";

Conditionals:

var a = 1;

if (a == 1) {
  print "1";
} else {
  print "not 1";
}

Loops:

var b = 1;

while (b < 5) {
  print b;
  b = b + 1;
}

for (var b = 1; b < 5; b = b + 1) {
  print b;
}

Functions:

fun say_hello(name) {
  return "Hello" + name + "!";
}
print say_hello("Kris");

Classes:

class Breakfast {
  init(meat, bread) {
    this.meat = meat;
    this.bread = bread;
  }
}

class Brunch < Breakfast {
  init(meat, bread, drink) {
    super.init(meat, bread);
    this.drink = drink;
  }
}