[avar]

And write your shared business logic in what language? If it's a C library perhaps you could do this on iOS and Android, but how is that going to run in a browser?

I'm aware of things like the LLVM based C to JS compilers, but they're not really viable for anything non-trivial.

That's why a lot of shops are writing the same logic N times in N languages and frameworks. It can actually be easier than having to target something these wildly different platforms share.

[lenkite]

If your business logic is in C - well you are in luck! Use emscripten to compile this to WASM and you can use it in the browser. This approach is very much viable. Large scale commercial web-applications like Figma are written in C++.

[buu700]

I'm aware of things like the LLVM based C to JS compilers, but they're not really viable for anything non-trivial.

emscripten/WebAssembly is pretty viable.

[iainmerrick]

Well, if “viable” means “doable but really fiddly”.

C/C++ is fine on iOS (at least when interoperating with Obj-C, Swift is trickier).

C/C++ is “doable but really fiddly” on Android, same as web. There’s a compiler toolchain but not much IDE support, and you have to do all the JNI marshaling yourself.

So C/C++ is only barely usable for common cross-platform code, and yet it’s the best option. What other language are you going to use?

It’s kind of ridiculous, but that’s the way it is. Programming languages are all the same in principle, but in practice they don’t interoperate well and they can’t easily be used everywhere.

[pjmlp]

> and you have to do all the JNI marshaling yourself.

After 10 years of Android, while I understand the goal is to force developers not to write unsafe native code, Android team could have already provide better tooling.

However they have always behaved as the NDK was something they had to offer, not something they actually wanted us to use.

[flohofwoe]

> but in practice they don’t interoperate well and they can’t easily be used everywhere.

...and yet, it's still much better than replicating the same code in different languages just to support different platforms.

The idea that a platform dictates the language to be used for creating applications on that platform has always been ridiculous, just because it was the status quo on the web for a bit over a decade doesn't mean it's a good idea that should be copied :/

[ryandrake]

I at least agree with this! It’s a big shame that the major mobile OS platforms bless only one or two languages for targeting their devices, and are at best neutral, at worst hostile to developing in other languages.

[buu700]

I'm not commenting on any other platforms, but I maintain a few C/WebAssembly libraries and they work exactly as expected without being unreasonably large. C-in-JS has been viable for a number of years now.

[iainmerrick]

I realise it works, I just don’t think it’s really useful for what was asked for, a way to write common cross-platform business logic for a platform-specific UI.

Unless there are some great new tools I’m not aware of, C on WebAssembly seems about the same as C on Android. You can compile stuff just fine, and run it, but actually connecting it up to any substantial UI written in JS/Java is going to be incredibly tedious.

For a computation library with well-defined inputs and outputs, and that “just works” and doesn’t need any debugging in situ, it makes a lot of sense. But I think business logic by definition is going to need a much richer interaction with the UI, and that’s what makes it hard.

[flohofwoe]

The interaction between C and Javascript offered by Emscripten is a lot better than JNI on Android. I wish the Android NDK would steal a few ideas from Emscripten, but all the Android teams at Google don't seem to be able to look outside the nice comfy bubble they've created for themselves.

With Emscripten, you can embed Javascript source code directly into the C code and then call the embedded JS function from the C side as well as C functions from inside Javascript.

E.g. JS embedded in C code:

https://github.com/floooh/sokol/blob/4c56a2ee15d81cac91b738b...

...called from C:

https://github.com/floooh/sokol/blob/4c56a2ee15d81cac91b738b...

...and a C function:

https://github.com/floooh/sokol/blob/4c56a2ee15d81cac91b738b...

...called from a JS function embedded in the C code:

https://github.com/floooh/sokol/blob/4c56a2ee15d81cac91b738b...

[iainmerrick]

Not bad! Sounds like the tooling has improved since I last looked.

How about debugging? Is it possible to step through a mix of C and JS stack frames?

[buu700]

Fair enough, and I strongly agree with the general point about the need for a solid cross-platform framework either way.

I don't see why you couldn't write your entire business logic, state management, etc. in C or Rust and treat it effectively like a client-side server, but I've never used wasm in that way so I can't speak from experience there. Either way, I can certainly see how that would require some extra effort, and of course it would only really be useful for applications that don't offload most of their work to a server.

[_-___________-_]

Generally speaking the "connecting it up" between c/wasm + js or C + java/kotlin on android can be completely automated with codegen. It's really not tedious at all.