Too bad Apple hasn't shown much interest in supporting Swift on other platforms; I know efforts exist but they all seem like second-class citizens. I don't really want to invest the time learning a new language that's locked to a single ecosystem.
That's a bit of an overstatement, Swift isn't really in the same ballpark than C++. Its performance characteristics are more the like of a managed language.
In the ixi driver implementation[1], they ended-up with results comparable to JavaScript in terms of throughput[2], and C# in terms of latency [3].
[1]: https://github.com/ixy-languages/ixy-languages/blob/master/R...
[2]: https://github.com/ixy-languages/ixy-languages/raw/master/im...
[3]: https://github.com/ixy-languages/ixy-languages/raw/master/im...
Still, Swift definitely makes some compromises when it comes to performance. ARC is pretty costly in general (in terms of time, it's pretty cheap memory-wise), thanks to heavy use of atomic operations, and copy-on-write for value types has really nice properties as far as making it easy to write correct code, but it can result in unnecessary data duplication which is hard to optimize since you're basically at the mercy of the compiler to make it mode efficient.
A lot of these problems have possible solutions which haven't been implemented yet - in the long term I'm curious how much performance could be improved since I think Swift really could be the "sweet spot" language in terms of performance and usability.
https://swift.org/download/#releases
https://www.digitalocean.com/community/tutorials/how-to-inst...
I’m not sure what’s missing as far as libraries, other than UIKit.
Still, to truly compete it would need to have Windows support too. And ideally real buy-in from at least one other major tech company.
The IBM Swift Sandbox is no longer available as of January 2018.
"Support" is the kicker - I consider C# and C++ to have Windows Support because the platform vendor publishes and provides support for their own developer tools.
Do you mean that, or maybe something closer to the level of "Support" where interested parties submit improvements, and platforms are included in the CI/CD process?
It's not from Microsoft directly, but it's worth noting that LSP support for Swift is under active development. VSCode is probably currently the second-best IDE for Swift development.
edit:
If you want you can use Swift on Google Colab right now:
https://colab.research.google.com/github/tensorflow/swift/bl...
It's quite usable. A couple years ago, I tried Swift for Linux when it came out, and it was a dreadful experience. But now I do things with Swift in Docker containers and basically don't think about it.
There's a few things which aren't implemented (IIRC things like XML parsing support) but it's mostly things I wouldn't use or would use a library for anyway.
Actually ABI-resilience is not the default, it is enabled by a compiler flag.
In addition to that, there are some current compiler limitations when it comes to cross-module usage of generics and inlining that affect performance. But those are not by design and can be improved in future compiler versions.
High level languages are fat, inefficient, rigid and what every large corporation wants, because they share so much in common.