If you're allocating most things from a set of arenas alive for the same scope, Rust's borrow checker complexity almost entirely fades away. You'll have one lifetime for all inputs and outputs of your functions, so the inferred lifetimes will always be correct. If you have multiple arenas being allocated from with different scopes, you're asking for trouble with the Zig model while the Rust borrow checker will keep which data is from which arena straight.