universal callback/continuable/thunk generator runner

run.js

function run(generator) {
  // Pass in resume for no-wrap function calls
  var iterator = generator(resume);
  var data = null, yielded = false;
  
  next();
  check();
  
  function next(item) {
    var cont = iterator.next(item).value;
    // Pass in resume to continuables if one was yielded.
    if (typeof cont === "function") cont(resume());
    yielded = true;
  }
  
  function resume() {
    var done = false;
    return function () {
      if (done) return;
      done = true;
      data = arguments;
      check();
    };
  }
  
  function check() {
    while (data && yielded) {
      var err = data[0];
      var item = data[1];
      data = null;
      yielded = false;
      if (err) return iterator.throw(err);
      next(item);
      yielded = true;
    }
  }

}

But if you use resume mode with the shared callback, things get messy

I briefly responded on twitter, but to elaborate a bit more... isn't a nasty exception a good thing if you have async code invoking a callback multiple times? If that's happening, there's clearly a bug and I imagine it would be best to "die early and die often" in that case, rather than simply ignore it. Granted, the thunk-style approach could choose to raise a more descriptive error in that case (+1 on that from me, anyway).

Hi, creationix.
May I ask you a question?

In the following code, you pass an argument to iterator.next() method.

10    var cont = iterator.next(item).value;

But whenever I pass any value to iterator.next(), there's nothing to happen.

var x = function()* {
    yield true;
}
var y = x();
y.next('foo'); //return true

What's the meaning of passing an argument to iterator.next() ?