> Although much code can be optimized to get it to run 10-15% faster, if that comes at the expense of legibility then such "feature" get rejected nowadays.
Makes sense, and I'd probably make the same call if I was a maintainer and someone submitted a patch which increased performance at the cost of maintainability...
> Translating an existing codebase into a language that makes things more difficult¹ and (because of that) has (and most likely will have) fewer engineers willing to working in it looks very much akin to applying legibility-affecting optimizations to me.
Here I have to personally disagree. I think that Rust is easier than both C and C++. Especially when coming into an already existing project.
The chance of me contributing to a Rust project is higher than to a C project, because I feel more comfortable in knowing that my code is "correct". It's also easier to match the "style" since most Rust projects follow the same structures and patterns, whereas in C it can vary wildly.
E.g. I contributed my first feature to Valkey (Redis fork, C codebase) recently, and figuring out how the tests worked took me quite some time. In fact, in the end I couldn't figure out how to run a specific test so I just ran all tests and grepped the output for my test name. But the tests take tens of minutes to run so this was sub-optimal. On the other hand, 99% of all Rust projects use `cargo test`, and to run a single test I can just click the play button in my editor (Zed) that shows up next to the test (or `cargo test "testname"`).
(with this said, I think that Valkey is a really well structured code base! Great work on their part)
Anyhow, this is just to illustrate my experience. I'm sure that for someone more used to C or C++ they would be more productive in that. And I could go on for ages on all the features that make me miss Rust every day at work when I have to work in other languages, especially algebraic data types!