Generators demo

//Generators 

// Remember functions?
function doA() {
  console.log('did A');
}
function doB() {
  console.log('did B')
}
function justAFxn() {
  doA();
  doB()
}

justAFxn()

//Yielding values
var helloWorld = function*() {
  yield 'hello';
  yield 'world';
}

var gen = helloWorld();
var a = gen.next();
console.log('from a we get: \n', a);

var b = gen.next();
console.log('from b we get: \n', b);

//Feeding values
var c = gen.next();
console.log('from c we get: \n', c)
var d = gen.next()
console.log(d)
//Feeding values

var ohHai = function*() {
  var x = yield 'hello';
  yield x + ' world';
}

var gen = ohHai();
var a = gen.next();
console.log('from a we get: \n', a)
var b = gen.next('rutabega');
console.log('from b we get: \n', b)









//Use cases: getting stuff from a database

// how we're used to seeing it done
asyncFunc('http://example.com', result => {
    console.log(result);
});

// with a Promise
asyncFunc('http://example.com')
.then(result => {
    console.log(result);
});

// with a Generator
Q.spawn(function* () {
    let result = yield asyncFunc('http://www.youthebomb.com');
    console.log(result);
});


/*
Resources:
"No promises: asynchronous JavaScript with only generators."
  http://2ality.com/2015/03/no-promises.html
  
"The Hidden Power of ES6 Generators: Observable Async Flow Control."
  https://medium.com/javascript-scene/the-hidden-power-of-es6-generators-observable-async-flow-control-cfa4c7f31435

*/