Relation with Node 12.3 `Readable.from`

[Tyler-Murphy]

It was added in node v12.3: https://nodejs.org/api/stream.html#stream_stream_readable_from_iterable_options.

I've used this library, but I just discovered that node now has a helper to do the same thing. It seems the only major difference is that you can't pass a generator function directly.

I think it'd be helpful to add a note to the readme to point people to the built-in solution, and explain the differences so that people can decide which to use.

[julien-f]

Indeed, it's very different, the ability to create a stream with a generator is the main goal of this library, for instance, I'm using it to generate a synthetic VHD file from a chain of delta VHD files, which would, IMHO be difficult to do with the stream API, even more when correctly handling back-pressure.

Anyway, I agree with that a note would be nice, feel free to open a PR 🙂

Edit: I think I was wrong, it appear equivalent to this library, what are the differences?

[Tyler-Murphy]

I may be wrong, since I haven't used this feature, but I think async-iterator-to-stream supports this pattern, where a generator function can be bound, as in the createReadStream in the readme:

const makeCountStream = asyncIteratorToStream(function * count () {
  yield 1
  yield 2
  ...
})

makeCountStream().pipe(process.stdout)

stream.Readable.from only accepts iterables, not generators. Meaning that to accomplish the same thing you'd have to do this:

async function * count () {
  yield 1
  yield 2
  ...
}

const makeCountStream = () => stream.Readable.from(count())

makeCountStream().pipe(process.stdout)

I don't think this is supported:

stream.Readable.from(function * doSomething () {
  yield 1
  yield 2
  ...
})

Either way, it seems like a minor difference. I'll open a PR!

[julien-f]

AFAIK the differences are:

• ability to create stream factory from (async) generators
• support Node >= 6
• support sync generators yielding promises instead of async generators

I think, as soon as the new Readable.from is included in readable-stream, I will migrate to using this for recent versions of Node.