Design Proposal - Kotlin

[birkskyum]

See proposal here

[lseelenbinder]

I would support this transition. Kotlin is much nicer to use than otherwise.

My only request would be to ensure bytecode compatibility for older versions, which is likely a few settings we will already need to adjust.

[birkskyum]

bytecode compatibility

Absolutely. My understanding is that the bytecode won't be identical, but it should be possible to make it compatible.

[birkskyum]

@wipfli , just putting your comment here to collect feedback in one place.

Thanks @birkskyum. I think Kotlin is the right language for Android. Let's wait with this pull request until we decided on #420.

[nvanfleet]

This is interesting, I wonder if we should consider migrating the iOS side to Swift?

[birkskyum]

@nvanfleet , if you investigate the Swift topic, and find that it's likely advantageous and have an idea about how we can do it, feel to make a design proposal to get some feedback. It's probably a good idea to cover possible changes in build size, the options for incremental adoption with bridge-headers and [Project]-swift.h, but it would be great to have a proposal to consider. Two sidenotes:

• We currently have an issue with NSExpression in obj-c that breaks our CI-pipeline, but this should be fixed if the code is ported to swift. Refactor NSExpression unit tests #421

[atierian]

I'm also in support of this, and would like to see a similar move on the Darwin side to Swift. I'm curious about how this would work technically though. AFAIK Kotlin doesn't have direct interoperability with C++ (please correct me if I'm wrong). That would mean that it would have to through JNI(?) or we'd have to make an ObjC or C wrapper around the C++ code for Kotlin to consume? Or does the Android SDK expose Kotlin APIs that would cover our needs?

There are similar limitations on the Darwin side as well. However Swift <-> C++ interop is actively being designed and implementing by a Swift language workgroup I'm on. Here's the current status. This would be a non-issue on the Darwin side if we went to Metal, but that's a larger conversation and I don't want to hijack your proposal here 😄.

[birkskyum]

@atierian , it seems like there's a lot of interest in swift, so could you maybe make a PR with design proposal for us to discuss?

Regarding the C++ interop, we're going to tidy up the C++ core so we can make bindings to a range of targets easier, probably with SWIG or similar. I imagine that will also be the best approach for Kotlin.

[atierian]

Yea, I'll write up a design proposal on it.
@nvanfleet happy to collaborate on it if you're interested.

[nvanfleet]

Yea, I'll write up a design proposal on it.
@nvanfleet happy to collaborate on it if you're interested.

Sure I'd be happy to discuss it!