Arcshift - an Arc that can be updated

I've gone and written a thing: https://crates.io/crates/arcshift

It's like Arc, with the same memory footprint as Arc, but with support for updating the value pointed to.

I was inspired by the excellent "arcswap"-crate, but Arcshift has a slightly different purpose and a different implementation.

It's a bit niche, but I'm very interested in hearing any opinions or comments!

I've written a sort of blog-post about it, it's in the Readme displayed at the crates.io-link above.