functional practice - promise map

index.js

const R = require('ramda');
const Promise = require('es6-promise').Promise;
const pMap = require('./promise-map');

function get(method) {
  return Promise[method]({
    addresses: [
      { street: 'street a' },
      { street: 'street b' },
      { street: 'street c' }
    ]
  })
}

const firstStreet = R.compose(R.nth(0), R.path(['addresses']));
const secondStreet = R.compose(R.nth(1), R.path(['addresses']));

function getFirstStreet() {
  return get().then(firstStreet);
}

const getFirstStreet2 = R.compose(pMap(firstStreet, secondStreet), get);

const getFirst2Streets = R.compose(
  pMap(R.map(firstStreet), secondStreet),
  Promise.all.bind(Promise),
  R.call(R.useWith(Array, get, get))
);

const a = getFirst2Streets('resolve', 'resolve')
  .then(console.log.bind(console))
  .catch(console.log.bind(console));

promise-map.js

const R = require('ramda');
const Promise = require('es6-promise').Promise;

module.exports = R.curry(function(resolve, reject, promise) {
  if (promise.constructor == Promise) {
    return promise.then(resolve, reject || R.identity);
  } else {
    return Promise.resolve(promise);
  }
});