Deprecate when.iterate and when.unfold

[briancavalier]

In favor of most.js streams, which have much nicer versions of both, complete with filtering, transforming, reducing, etc.

[astorije]

Hi @briancavalier,

It seems to me that the version in most.js allows for creating infinite structures while when.iterate was nice to create an infinite sequence of actions. Although I might be wrong in the design, in this previous sentence, I couldn't find an example on how to translate the following code using when.iterate into code using most.iterate or most.unfold:

require('when').iterate(function(x) {
    return x+1;
}, function(x) {
    return x >= 10;
}, function(x) {
    console.log(x);
}, 0).done();

Could you help? In particular, how to rig the end condition and the handler in when.iterate (if possible)?

[briancavalier]

most.js allows for creating infinite structures while when.iterate was nice to create an infinite sequence of actions

That's quite an interesting distinction, @astorije. I'll give that some thought. I've been considering other options for keeping when.unfold/iterate. For example, we could move them to a contrib package, like when-unfold or something, since they are less commonly used.

I couldn't find an example on how to translate the following code

I'll take a shot at it :) Using ES6 for brevity, here's with most.iterate

most.iterate(x => x+1, 0)
    .takeWhile(x => x < 10)
    .observe(x => console.log(x))
    .done();

And with most.unfold:

most.unfold(x => { value: x, seed: x+1, done: x >= 10 }, 0)
    .observe(x => console.log(x))
    .done();

Does that help? Let me know if you any questions!

[astorije]

It does help, thanks a lot @briancavalier!

I now have a better understanding of what I want to do and how to plug (when|most).iterate to it. However, I do not need a full-featured lib for that, and will end up using a custom version of when.iterate.

That might confirm that when.iterate is better off its own package, but that's your call. All in all, I'm happy I could find the code of when.iterate and when.unfold because they really correspond to what I want to do, without relying on 4 different methods, but that might only be good for my current use case...

[mnahkies]

@briancavalier The API documentation does not seem to reflect this deprecation, is this intentional?

Additionally, the documentation does not state that the predicate may return a promise for a value whilst the code and tests indicate that it can.

https://github.com/cujojs/when/blob/master/docs/api.md#whenunfold