Requires complete listener

[elniffi]

So just using this very basic example below to start messing around with xstream in Node.JS it looks like the code assumes there is a "complete" event handler. If I remove it it actually throws an exception when it triggers because it's trying to a run a function that does not exist.

'use strict';

var xs = require('xstream').default;

var stream = xs.periodic(50)
    .filter(i => i % 2 === 0)
    .map(i => i * 2)
    .endWhen(xs.periodic(5000).take(1));

stream.addListener({
    next: i => console.log(i)
});

/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:874
            a[0]._c();
                 ^

TypeError: a[0]._c is not a function
    at Stream._c (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:874:18)
    at EndWhenOperator.end (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:308:18)
    at OtherListener._n (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:278:17)
    at Stream._n (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:849:18)
    at TakeOperator._n (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:789:17)
    at Stream._n (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:849:18)
    at Timeout.intervalHandler [as _repeat] (/Users/elniffi/Documents/Code/xstream-testing/node_modules/xstream/lib/core.js:196:45)
    at Timeout.wrapper [as _onTimeout] (timers.js:408:11)
    at tryOnTimeout (timers.js:224:11)
    at Timer.listOnTimeout (timers.js:198:5)

Using Node.js 5.10.1 and Xstream 1.0.2

[staltz]

Hi, thank you for taking your time to send us this issue. We appreciate it, however, this is by design. It's required, for two reasons:

• There should not be many addListener uses in your code. xstream is not meant for that, it assumes you have a few uses (hence manageable amount) of that
• Having addListener polymorphic (types addListener(next: Function) and addListener(listener)) would be a bit of a hit on performance, and we try to keep it fast.

If you don't need to listen to error nor complete, just pass a noop function () => {}.

I'll close this issue unless after discussion we agree that it would make sense to change. Thank you for your time and I hope it's ok with you.

[elniffi]

That's totally fine with me, thank you for the response and great work!