Harmony Generators vs Promisses Libs

gistfile1.js

var step = 0;

async.waterfall([
    function (next){
        step = 1;
        getJson('/country', function(data) { next(null, data); });
    },
    function (country, next){
        step = 2;
        getJson('/weather', function(data) { next(null, country, data); });
    },
    function (country, weather, next){
        step = 3;
        getJson('/stock_exchange', function(data) { next(null, country, weather, data); });
    }
], function (country, weather, stockExchange) {
  if (err) {
    console.log("Died at step:" + step);
  } else {
    console.dir({
      country: country,
      weather: weather,
      stockExchange: stockExchange
    });
  }
});

// vs:

// see: https://gist.github.com/creationix/5544019
run(function* () {
  var country, weather, stockExchange, step = 1;
  try {
    step++;
    country = yield getJson('/country');
    step++;
    weather = yield getJson('/weather');
    step++;
    stockExchange = yield getJson('/stock_exchange');
    console.dir({
      country: country,
      weather: weather,
      stockExchange: stockExchange
    });
  } catch(err) {
    console.log("Died at step:" + step);
  }
})();