Preparing a function to repeatedly use in a generator runner

Question

I'm using a nodejs telnet implementation which uses an event to provide notification each time data is received from a telnet client, which can be subscribed as follows:

client.on('data', [callback]);

I'm also using a generator runner (generator-runner on npm) to execute workflows.

The problem I'm having is that yielding values in this way requires something more like a promise: a single delegate passed on to process a single value. How would I go about writing a function which could be placed in the generator yield statements, and could be repeated every time I want to yield more input?

I've tried using Baconjs for this, but I don't think there's a way to block waiting for a single value on a stream, at least I can't find such a method.

I'm open to any advice. My only real requirement is that I be able to place my workflows in a flat block of code without chaining promises.

Here's the code I've got mocked up, which simply doesn't work:

var requirejs = require('requirejs');
requirejs(['telnet', 'baconjs', 'colourise', 'lodash', 'generator-runner'], function(Telnet, Bacon, Colourise, _, Async) {
    var configureClient = client => {
        client.do.transmit_binary();
    };

    Telnet.createServer(client => {
        var session = {
            connectedAt: Date.now(),
            user: { }
        },
        write = _.compose(_.bind(client.write, client), Colourise.encode),
        readStream = Bacon.fromBinder(function (sink) {
            client.on('data', function (data) {
                sink({ client : client, data : data, session : session });
            })}),
        read = () => readStream.take(1).toPromise();

        configureClient(client);
        write("%xxWelcome!\r\n")

        Async(function*(){
            write("Username: ");
            var user = yield read();
            console.write("Username entered: " + user);

            write("Password: ");
            var password = yield read();
            console.write("Password entered: " + password);
        });
    }).listen(8100);
});

Answer 1

I've gotten this working by using 'fromEvent' in Baconjs and using 'firstToPromise'. I was getting exceptions thrown from 'fromBinding', so I don't know what was up there, but it slowed down my progress a lot.

Below is the simplified and working code. Requires ES6 (I used node flags --harmony and --harmony_generators.)

On a side note, I'm hugely excited about the implications of this technique!

var requirejs = require('requirejs');
requirejs(['telnet', 'baconjs', 'generator-runner', 'lodash'],
    function(Telnet, Bacon, Async, _) {
        var configureClient = client => {
            client.do.transmit_binary();
        };

        Telnet.createServer(client => {
            var write = _.bind(client.write, client),
                readStream = Bacon.fromEvent(client, 'data'),
                readAsync = () => readStream.firstToPromise();

            configureClient(client);
            write("Welcome!\r\n")

            Async(function*(){
                write("Username: ");
                var user = yield readAsync();
                console.log("Username entered: " + user);

                write("Password: ");
                var password = yield readAsync();
                console.log("Password entered: " + password);
            });
        }).listen(8100);
    }
);