To promisify csv-parse using Bluebird

bluebird-csv.js

"use strict";

var fs= require('fs');
var Promise = require('bluebird');
var parse= Promise.promisify(require('csv-parse'));

var file = fs.readFileSync('test.csv', 'utf8');
var headerKeys;
var options ={
  trim: true,
  columns: function(header) {
    headerKeys = header;
    console.log('header: ', header);
  }
};
var users = [];

parse(file, options).then(function(rows) {
  rows.forEach(function(r) {
    var user = {};
    headerKeys.forEach(function(k, i) {
      user[k] = r[i];
    });
    users.push(user);
  });
  console.log(users);
}).catch(function(err) {
  console.error(err);
});

streaming example would be great. imagine a 2GB csv file? this would kill the system, reading whole file into memory, twice, once for file, again for each row.