RFC: onErrorReturn() operator about redux-observable

[jayphelps]

@BerkeleyTrue there's some internal discussion around this right now. There is a high probability RxJS will start adding more operators (like this one), even though the last public discussion in that thread ReactiveX/rxjs#1928 (and others) was that we didn't want to add more.

The big kicker is file size bloat for UMD and import Rx from 'rxjs' usage. To still keep that lean, we're considering shifting a number of existing operators (and any new ones) to separate builds for UMD and namespaced for CJS/ES.

e.g.

import Rx from 'rxjs';
import 'rxjs/kitchen-sink';
// or
// import 'rxjs/kitch-sink/add/operator/onErrorReturn';

This would be an easier decision if RxJS had a true monorepo, but several of us have tried and all gave up (for now) frustrated with our super super complicated build requirements. It sounds silly, but we all thought "it can't be that hard" and ultimately came out saying "mother of gawd..."

No promises, either way. But for now I'm waiting until a more formal decision is made around this for RxJS.

Others are (of course) certainly welcome to take my code from ReactiveX/rxjs#1928 and either keep a local copy in their app or publish their own library.

As an aside, we're going to start being a little more formal with RxJS meetings--now being held every 2 weeks--I'm proposing to the group next meeting that we release meeting agenda and notes similar to reactjs/core-notes and emberjs/core-notes.

[jayphelps]

After discussing with numerous people, I think this is a great addition to core so I've made a PR for this. We'll bikeshed there. ReactiveX/rxjs#1928

[BerkeleyTrue]

This is 99.99% of my use of the catch operator.

[BerkeleyTrue]

Since this will not be added to core, are we adding an operator to this library?