Yes. A good example would be Firefox. Mozilla is gradually replacing core components of Firefox with replacements written in Rust. It is not cheap to do this wi

Yes. A good example would be Firefox. Mozilla is gradually replacing core components of Firefox with replacements written in Rust. It is not cheap to do this without causing regressions, but they have a great test suite and they know that it will save money in the long run. It increases performance, decreases memory usage, and most importantly it greatly reduces the defect rate. They’ll probably never bother to replace _all_ of the C++ code with Rust, because a lot of it works well or isn’t security–critical. They’ve been doing this since Rust 1.0, with measurable improvements in every release of the last few years.