Add the equivalent of concatMap

[denizcoskun]

concatMap is a quite useful operator in the Rx world and it was a bit disappointing that Combine didn't have a built-in equivalent of it until I found that flatMap behaves like concatMap when used correctly.

[freak4pc]

I'm not sure that's entirely true, there was a huge discussion about this in one of the slack channels and some folks mentioned it has some differences. I'll try to find that info.

[denizcoskun]

@freak4pc thanks, really appreciate that!

[denizcoskun]

I'm not sure that's entirely true, there was a huge discussion about this in one of the slack channels and some folks mentioned it has some differences. I'll try to find that info.

here's where I got the information: https://forums.swift.org/t/combine-what-are-those-multicast-functions-for/26677/26

[freak4pc]

I couldn't find anything against this claim, if you rebase this I'll merge it . Thanks!

[denizcoskun]

I couldn't find anything against this claim, if you rebase this I'll merge it . Thanks!

@freak4pc thanks, it is rebased now.

[freak4pc]

Hey @denizcoskun -

There was an interesting research and discussion in CombineExt which seems to indicate this variation isn't quite similar to concatMap in all forms.

What do you think?

CombineCommunity/CombineExt#68