fetch.js using flutures

fetch.js

const fetch = require('node-fetch')
const Future = require('fluture')
const fs = require('fs')

const BASEURL = 'https://api.github.com/licenses'

const headers = {
    headers: {
        'Accept': 'application/vnd.github.drax-preview+json'
    }
}

//    fetchf :: Url -> Future Error Response
const fetchf = Future.fromPromise2(fetch)

//    writeLicense :: (File Path String, Contents String) -> Future Error Success and Unit
const writeLicense = (file, contents) =>
    Future.node(done => fs.writeFile(file, contents, done))

//    getLicenseList :: (Url, Options) -> Future Error Json([licensepaths])
const getLicenseList = fetchf(BASEURL, headers)
    .chain(res => Future.fromPromise(_ => res.json(), 0))

const getLicense = json =>
    fetchf(BASEURL + '/' + json.key, headers)
    .chain(res => Future.fromPromise(_ => res.json(), 0))
    .chain(json => json['key'] ? Future.of(json) : Future.reject('Invalid JSON Response: Invalid Key'))
    .chain(json => writeLicense(__dirname + '/licenses/' + json.key, json.body))

getLicenseList
    .chain(x => Future.of(x.map(getLicense)))
    .chain(Future.parallel(20))
    .fork(console.error, _ => console.log('Fetched licenses'))