C# is GC'd so massive memory hit, and also not a language you can have in a kernel. Go: GC again, so no go. Rust: most sane of the examples you've given. App

C# is GC'd so massive memory hit, and also not a language you can have in a kernel. Go: GC again, so no go. Rust: most sane of the examples you've given. Apple has already started migrating to Swift which is a memory safe language. However the real reasons Rust and Go aren't feasible is that they're both essentially all-or-nothing, and neither offers even the most basic semblance of ABI compatibility. Their only nod to ABI stability is "use FFI to C" which means your APIs remain unsafe, and doesn't work for non-C languages without all your system APIs having other languages layered on top. Swift at least lets you replace individual objc classes one at a time, and is ABI stable, but has no C++ interaction.