The following can’t be resolved. The culprit seems to be the

BiFunction

, but I can’t figure out what specifically I’ve done incorrectly

val one = Observable.fromIterable(listOf(1,2,3))
        val two = Observable.fromIterable(listOf(4,5,6))
        Observable.combineLatest(one, two, BiFunction{ p1:Int, p2:Int -> p1+p2})

have you considered using RxKotlin ? It makes working with the types in operators like

zip

and

combineLatest

much easier: https://github.com/ReactiveX/RxKotlin

Thank you for the recommendation, I’ll give it a shot. However, it would still be nice to understand why my example doesn’t work

Actually, copy pasting your code into my IDE works and compiles

I just realized, I think I have the wrong import for

BiFunction

it should be from

io.reactivex.functions

Yeah, I had the java one imported. Thanks for the help!

I've hit that issue so many times. It's brutal.

In IDE preferences, you can go to Editor > General > Auto Import, and there's a list of classes you can exclude from auto-import. Very helpful for avoiding this sort of mistake.