very basic example of how flow control can be accomplished with generators

threads.js

var fs = require('fs');

function thread(fn) {  
  var gen = fn();
  function next(err, res) {
    var ret = gen.next(res);
    if (ret.done) return;
    ret.value(next);
  }

  next();
}

thread(function *() {  
  var a = yield read('Readme.md');
  var b = yield read('package.json');
  console.log(a);
  console.log(b);
});

function read(path) {  
  return function(cb) {
    fs.readFile(path, 'utf8', cb);
  }
}