jlox

A Lox interpreter made along with Robert Nystrom's wonderful book "Crafting Interpreters".

Differences from the original version

The interpreter supports features that were suggested to be added in the Challenges sections.

• Dividing by zero is an error

  1 / 0; // Error!

• Accessing an uninitialized variable is an error

  var a;
  print a; // Error!

• Not using a local variable is an error

  {
      var a = "unused";
      // Error!
  }

• C-style comments

  /* This is a comment. */

• The ternary operator

  print 2 == 3 ? "How?" : "Nice"; // Prints "Nice".

• Concatenating strings with other types

  print "Hello " + 123; // Prints "Hello 123".

• The REPL accepts raw expressions and prints their values

  > 2 + 3
  5

• Break statements

  // Prints "4".
  for (var i = 0; i < 10; i = i + 1) {
      if (i * i == 16) {
          print i;
          break;
      }
  }

• Anonymous functions

  var hello = fun() {
      print "Hello";
  };
  hello(); // Prints "Hello".

• Class methods

  class Test {
      class greet() {
          print "Hello!";
      }
  }
  Test.greet(); // Prints "Hello!".