Funny you mention Rust - one of Hares lead devs (and I believe the original creator), Drew DeVault, has been pretty vocal about his dislike for Rust, especially in the low-level and Linux kernel world. Here's an article by him about the subject:

https://drewdevault.com/2022/10/03/Does-Rust-belong-in-Linux.html

IIRC, Hare has more of a "trust the programmer" approach to things such as memory management. As a programmer who who trusts no one and especially not myself, I don't think Hare is for me (and i disagree wit a lot of Drews points.) But that's just my two cents. The language itself seems pretty neat still, but I think it's got very different design goals