highland.js

'use strict'

const _ = require('highland')

// Fake dagservice get
const get = (hash, cb) => {
  cb(null, {
    type: 'file',
    data: Math.random() + hash,
    links: []
  })
}

// Turn our callback function into a stream generator
const getStream = _.wrapCallback(get)

const highFileExporter = (node, name, dir) => {
  let stream

  const unmarshal = (data) => data

  if (node.links.length === 0) {
    stream = _(unmarshal(node.data))
  } else {
    stream = _(node.links)
      .flatMap(getStream)
      .map((res) => unmarshal(res.data))
  }

  return {
    stream,
    path: name,
    dir
  }
}

const res = highFileExporter({
  links: ['hello', 'world']
}, 'highland.txt', 'awesome/me')
let i = 0

console.log('got result', res.path, res.dir)
res.stream.each((data) => {
  console.log('got my data %s', ++i, data)
}).done(() => {})

output.txt

❯ node highland.js
got result highland.txt awesome/me
got my data 1 0.7449878605548292hello
got my data 2 0.36780680948868394world