tryMap & flatMap operators

[alcarvalho]

ReactiveCocoa has an operator which is called tryMap is not the best name but I think we should have something similar on RxSwift.

On RxJava, the map itself is able to handle any runtime errors and just send an error event in case something throws inside the map operator. That would be the nicest way to have it. And maybe with Swift 2 will be able to.

But for now, how can we approach that?

Another operator that's really, really missing is a flatMap, don't you think?

I guess I could help with that, but I am creating this issue to discuss before.

[kzaher]

Haha,
I have good sense for timing :)

flatMap will be ported in a few days, and it's in the process of porting.

For functions that can accept selector, there is usually *orDie overload that returns RxResult. This is documented little confusing right now in README.md. I'll fix that.

The orDie suffix was chosen as a explanation what will happen if function fails. Entire sink chain will be disposed. Maybe I should reconsider the wording in next 2.0 version.

So in case of map, you have mapOrDie (you can return success(value) or failure(error) from this one).

You have filter (that can never fail), and filterOrDie that can return error.

...

[alcarvalho]

That's great news! 👍
And thank you for the explanation on the orDie operators. 😄

[kzaher]

I usually learn where I've messed something when people are confused, so I'm solving one confusion at a time :)

Feel free to let me know if there are other pain points.

[kzaher]

FYI, flatMap has entered develop branch, and he brought two friends with him :)

It will be released end week with other improvements.

[alcarvalho]

Great, @kzaher! Thank you...

I was thinking about the OrDie functions. Maybe it would be clearer if they were called something like 'assertMap' as a prefix. Or even "mapOrError".

I have to confess I was afraid to use these "OrDie" functions at first because of their names, hahaha...

[kzaher]

Then I'm glad they are working as designed and scare people :) That was my actual intention ;)

Maybe I should rename catch to resurrect :)))

[alcarvalho]

That would be awesome! 😝

[kzaher]

Hi,
so flatMap has entered the building :)
As for orDie suffix, I don't think it's ideal, but don't think it's horrible either :)

I think that your other suggestion you've made on Slack orFail could be maybe better then orDie, but I'll need to think about if and when to make those changes.

For now, I'll close this issue since flatMap is added to RxSwift, but you can open new one with orFail suggestion if you like.