The borrow checker is Cyclone's region-based memory management combined with linear/affine types.

Edit: As an aside, I found a Reddit post the other day asserting that the Cyclone developers knew that it would never become mainstream but thought it was important because other languages would adopt it's ideas. It's amazing that they predicted that regions would be picked up later on by Rust.

You can find it here: https://twitter.com/tmccrmck/status/850465514807631872

That's the point. IIRC it's called Rust to allude to the fact that there's nothing really new in the language

Compile-time checking of owned and borrowed references was in Vala, a C#-inspired language for the GNOME ecosystem, four years earlier.

Doesn't Vala use reference counting? [1] I'm not actually sure; do you have some pointers I could read here?

1: http://www.vala-project.org/doc/vala/Overview.html#Memory_ma...

From what I remember, it just uses GLib's system for implementing reference-counted pointers in C and is equivalent to using Rc<T> or Arc<T> everywhere in Rust.

Yeah, that's what I thought. Which is very different than most Rust code!

Yes, but so does Rust. Reference counting is orthogonal to, although related to, to borrow checking.

Vala's wiki has a page all about its ownership mechanism: https://wiki.gnome.org/Projects/Vala/Ownership

Rust does not use reference counting for ownership, or borrow checking. It is true that you can introduce it for your own types though, with Rc/Arc. That's not really "rust using" it though; it's just a library.

Thanks for the link, I'll dig in!