[jabwd]

This makes me think you haven't really tried it ever? Sure writing a hello world is something but, one of the best features of Swift on the server side is that it seamlessly interopts with anything C (and nowadays C++, though that is after my time).

I wrote an entire, well performing backend in Swift because I could just directly plug in to already existing libraries without having ot provide a whole bunch of "FFI" glue.

All the other languages you suggest is something that Swift excels at while staying performant (also none of those have an IDE like Xcode so idk why you even bring it up). Though for actual systems programming I don't think Rust can be beaten by Swift, simply because of its more explicit (and therefore confronting) nature.

[robertjpayne]

We use server side Swift extensively since about 2016 for decent production load and it's easily one of the worst decisions I've ever made.

- C/C++ interop is great but if we wanted to use C/C++ libraries why use Swift at all? It's annoying to interop with them even if there is no FFI and still requires a lot of glue code for memory management etc…

- The stdlib (Foundation) is not identical on all platforms even today. This has been a major thorn as releases constantly have discrepancies and subtle bugs that are hard to diagnose and track down. Even Swift 6.1 broke non UTF-8 string encodings by just returning "nil" on Linux and took until Swift 6.2 to be fixed (nearly a year).

- The compile times are awful, with a large Swift codebase it takes us ~10-20 minutes to compile our backend Docker container and thus deployments to dev take that long and it's only going to keep getting longer as Apple seemingly has no interest in making the Swift toolchain much faster and Swift has a fatal flaw in it's design around bi-directional type inference that ensure it can never be compiled fast.

- Talent is impossible to find. Yes lots of people know Swift for iOS apps but nobody knows Swift for server code and a backend dev is a very different skillset than an app dev.

We chose it because it allowed us to share some domain code between our flagship iOS product and the server with a custom built sync engine but as our platform has grown it's just gotten harder and harder to justify keeping Swift on the server which is why we're actively migrating off it.

[Redoubts]

> - The stdlib (Foundation) is not identical on all platforms even today. This has been a major thorn as releases constantly have discrepancies and subtle bugs that are hard to diagnose and track down. Even Swift 6.1 broke non UTF-8 string encodings by just returning "nil" on Linux and took until Swift 6.2 to be fixed (nearly a year).

sad, I was doing server side around v4/5 and this was the biggest issue at the time for me (lots of stuff was not implemented and you only found out at runtime). that this is still a problem is very disappointing...

[pjmlp]

Outside macOS/iOS devs wanting to share code with server side, I don't see a use case, given the more mature alternatives.