Glox

A Go implementaion of the tree walk interpreter for the Lox language. I wrote this version while reading the book Crafting Interpreters by Robert Nystrom.

Documentation

Installation

Download the latest binary from the Releases page as per your platform. Unzip the package, you'll have the glox binary. Running only ./glox will give you the interactive terminal or you can pass in the location of a glox script file to run a script e.g. ./glox hello.glox where hello.glox contains the glox script in the same directory as the glox binary.

Examples

Hello world:

// Your very first lox program.
print "Hello, world";

Variable declaration

var a = 5;
var b = 6;

var c = a + b;
print c; // prints 11

Loops

for (var i = 0; i < 5; i = i+1) {
  print i;
}

// prints 
// 0
// 1
// 2
// 3
// 4

Conditionals

var a = 5;
if (a >= 4) {
  print "a is greater than or equal to 4";
} else {
  print "a is less than 4";
}

Functions

fun printSum(a, b) {
  print a + b;
}

printSum(5, 6); // prints 11

// Closure
fun returnFunction() {
  var outside = "outside";

  fun inner() {
    print outside;
  }

  return inner;
}

var fn = returnFunction();
fn(); // prints outside

Classes

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

  cook() {
    print "Eggs a-fryin'!";
  }

  serve(who) {
    print "Enjoy your " + this.meat + " and " +
        this.bread + ", " + who + ".";
  }
}

// instantiate
var breakfast = Breakfast("sausage", "toast");
breakfast.serve("Sayantan"); // prints "Enjoy your sausage and toast, Sayantan".

Inheritence

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