// noprotect

​

// line above is for generators

// lodash/fp is `_`

​

// const _ = require('lodash/fp');

​

// Based on http://gajus.com/blog/2/the-definitive-guide-to-the-javascript-generators

​

const delayedFunc = _.curry((name, callback) => {

  setTimeout(() => {

    console.log(`calling callback(${name})`);

    // This is where we're calling the `advancer` with the `response`

    callback(name);

  }, 1000);

});

​

​

function controller(generator){

  const iterator = generator();

  let timesNextCalled = 0;

  const advancer = (response) => {

    // Notice that the iterator is a closure, so it can go to all the recursive calls.

    // Also, notice that this is where we send back the result from calling yield, so the

    // SECOND time this line is called, the value goes into variable `a`

    const state = iterator.next(response);

    timesNextCalled++;

    console.log(`state after iterator called ${timesNextCalled} times is`, state);

    // state has { value, done }

    if (!state.done) {

      // Note that the value is a function, the callback, which is the 

      // curried anonymous funcs below with the "advancer". Basically, this is

      // recursive. It's critical that that the value is a curried function!

      state.value(advancer);

    }

  }

​

  // First time advancer is called, there is no "response"

  advancer();

  return 'All Done! (but not yet with async operations)';

}

​

​

function* myGeneratorFunc() {

  console.log('These operations run in order.')

​

  // This is the curried function, that will take one more argument, the callback,

  // which is the "advancer" defined above.

  const a = yield delayedFunc('A'); 

  console.log("after first yield called");

  const b = yield delayedFunc('B');

  const c = yield delayedFunc('C');

  console.log(`After running all 3 delayed funcs, a = ${a}, b = ${b}, c = ${c}`);

  console.log('Done with sequential async operations.')

}

​

function run() {

  return controller(myGeneratorFunc);

}

​

console.log('About to call run');

const result = run();

console.log(`Done with run, result = ${result}`);