Rust's borrow checker is unique in the sense that it is production-ready. Cyclone is indeed prior art, but it's not as if it ever got beyond the research project stage.
Re:Why is Zig so Cool?
by johnisgood on Saturday November 08, 2025 @10:19AM
(#45857225)
I don't necessarily disagree, of course. That is why I like Odin the most so far, and perhaps C3.
Rust's borrow checker isn't unique either but was inspired by Cylone: https://en.wikipedia.org/wiki/Cyclone_(programming_language)
IMHO a programming language doesn't need a single USP, it just needs to include good existing ideas and (more importantly) exclude bad existing ideas (of course what's actually a good and bad idea is highly subjective, that's why we need many programming languages, not few).