clox

Compiler and bytecode VM for Lox from Crafting Interpreters.

The implementation has additional features, mainly coroutines, which are not part of the standard Lox.

Additional features

• coroutines

  // Async functions return promise that has to be awaited.
  async fun constant(c) { return c; }
  print constant(5); // <Promise>
  print await constant(5); // 5
  
  // `sleep` to wait in coroutine (doesn't block other coroutines).
  async fun delayedPrint(t, v) {
      sleep(t);
      print v;
  }
  
  // `yield` to do computation in parts to avoid blocking other coroutines.
  async fun fib(n) {
      var a = 1;
      var b = 2;
      for (var i = 0;i < n;i++) {
          yield;
          var c = a + b;
          a = b;
          b = c;
      }
      return a;
  }
  
  // Native functions for TCP server (see `examples` folder).

• string interpolation

  var a = 5;
  print "a is {a}";

• switch statement

  switch (value) {
      case 0: print "zero";
      case 1: print "one";
      case 2: {
          print "t";
          print "w";
          print "o";
      }
      default: print "default";
  }

• break and continue

• conditional operator

  print condition ? "true" : "false";

• post increment

  var a = 5;
  print a++; // 5
  print a;   // 6

• arrays

  // Array constructor
  var arr = Array(3, 0);
  arr[1] = 5;
  print arr; // [0, 5, 0]
  print arr.length; // 3
  
  // Array literals
  var lit = [1, [2, 3], [], [4]];
  print lit[1][1]; // 3

Native functions

Name	Arguments	Description
clock		Returns number of seconds since the program started.
sleep	duration_ms	Puts coroutine to sleep for duration milliseconds.
hasField	object, field	Returns whether object has field.
getField	object, field	Returns field value or throws runtime error if the field doesn't exist.
setField	object, field, value	Sets or overwrites the field.
deleteField	object, field	Deletes the field if it exists.
createServer		Returns server socket that is an argument to other functions.
serverListen	server, port	Starts listening on port or throws runtime error if the other process has already taken it.
serverAccept	server	Returns a promise of client socket, that will be resolved when client connects to the server.
socketRead	socket, max length	Return a promise of string of at most max length, that will be resolved when it reads from client.
socketWrite	socket, string	Returns a promise that will be resolved once the entirety of string has been written.
socketClose	socket	Closes client socket.