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Comment by eridius | Hacker News Reader

I'm not sure why "supported by both Google and Apple" is supposed to matter. Apple doesn't need to ship a Rust compiler for me to use Rust.

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1st tier tooling supported by the platform won't break yearly on every new OS version and you don't have to wait until your 2nd tier tooling developers gets around to fixing it.

The platform developers will do their best to keep 1st tier tooling working and fix it when it breaks.

Last I checked the Rust compiler doesn't output bitcode in the format Apple requires. So no Watch/TV apps.

Likely too much friction. Native environments benefit from using the expected IDE and tooling integration to build UI apps on respective platform. C or C++ is the best common supported language, and they didn't even like that.

Also the UI frameworks are being written in said preferred language these days, eg SwiftUI, and adding one additional language could be perceived as a pain.

Apple ships a C++ compiler but you can't use C++ with Apple's platform SDKs. IF you want to use C++ you need to write Obj-C++ glue code to access most of the system frameworks, including UI code.

I would look at it differently, i.e, obj-c++ is a valid supported language environment, that makes interopt with C++ pleasant at least compared to other interopt choices. Developers may choose to target Obj-C++ even out of preference.

Metal and driver SDKs require C++.

Metal is Obj-C.

Then try to write Metal shaders in Objective-C.

Metal shaders != Metal API. Metal API is Obj-C. Metal shaders are written in MSL (Metal Shading Language). C++ is still not involved, though MSL is admittedly based on C++.

Metal API ⊇ Metal Shaders, it is useless without them.

https://developer.apple.com/metal/Metal-Shading-Language-Spe...

"The Metal programming language is a C++14-based Specification with extensions and restrictions. Refer to the C++14 Specification (also known as the ISO/IEC JTC1/SC22/WG21 N4431 Language Specification) for a detailed description of the language grammar. This section and its subsections describe the modifications and restrictions to the C++14 language supported in Metal."

Also, the MSL and Objective-C compilers are built on top of LLVM, written in C++.

I don't know what point you're trying to make. MSL doesn't link with the rest of your program. No matter what language you use for your program, the shaders are written in MSL. For my program if I use Rust or C++ or Obj-C or Swift or a microscopic magnet and a very careful hand, I write my Metal shaders in MSL.

1 - MSL is a set of extensions on top of C++14

2 - Metal requires MSL

3 - IO Kit is a C++ framework for macOS, iOS, iPadOS and watchOS drivers

4 - Metal GPGPU drivers are written in IO Kit

5 - Metal is useless without MSL and GPGPU drivers

6 - Ergo, Metal requires C++

The fact that Metal itself requires the existence of C++ really has nothing to do with this topic though, which is whether there's any downside to writing your app in a language that Apple doesn't ship a compiler for. The fact that Metal shaders are written in a language based on C++ is irrelevant to this question, because it doesn't matter what language you pick for the rest of your app as Metal shaders don't link with your app. Swift has zero integration with C++ and yet I can write a Metal app using Swift, because the fact that the shaders are written in MSL has no impact on the fact that the app uses Swift.

And the language for writing drivers in is even more irrelevant because we're not talking about writing drivers. You can't write drivers in Swift either.

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