[rednafi]

Swift is a neat language, but it’s a hard sell for server-side software. The ecosystem is tiny, and there’s nothing you gain from using it instead of Go or Rust for infra / distsys.

Also, it works okay at best with VS Code, and you couldn’t pay me to use Xcode.

Kotlin tried doing similar things to gain adoption on the server side. But server-side programming is a crowded space, and people just don’t like writing distsys code in another JVM language. Swift’s story is a little better on that front.

If you want a quick-and-dirty language, Python and TypeScript do the job. For perf-sensitive, highly concurrent environments, Go is hard to compete against. A lot of ops tooling and infra code is written in Go. For systems programming and embedded code, Rust is a better choice.

So while it’s fun to think about what language X gives you in terms of syntax, in practice it’s rarely enough to pick a language like Swift for your next non-toy backend distsys work.

Also, Apple. Given their stance against free and open source software, I wouldn't be too thrilled to pick a language that works better in their walled garden.

[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.

[myko]

I have been using Swift Vapor for personal projects for awhile and it's great. I kind of regret it now on some projects since I use a lot of Go too and I miss the speed of compiling/testing when I'm using agentic coding (where my goal is to put the agent into virtuous loops leading to a success state) - it just takes longer in Swift.

[rednafi]

In agentic workflows, Go’s fast compiler and simple syntax make things so much easier.

I no longer write Python or JavaScript, even for trivial scripts. Why suffer sluggish performance or tooling nightmares when choosing a typed language no longer costs much?

As for Swift, it’s a harder sell. The docs aren’t there. The libraries aren’t that great. Apple-ism scares away a ton of folks, and the alternatives create less friction.

[pjmlp]

The target group for server-side software are iOS and macOS developers that also need a server component, thus like the JS folks, they get to use the same programming lanugage.