Rust Compiler Errors

In Rust, you do everything immutably and don't use the mutt keyword unless in unusual circumstances. So when I've tried to do maybe more intermediate advanced functional programming in Rust, like especially if I'm doing a lot of stuff with higher order functions,  I haven't had a great experience. It really, really take plucking those functional features of, yeah, immutability. We haven't gone too deep into that, that realm.