[tialaramex]

Having an arena allocator is completely unrelated. It's one of the features all of these languages out of the Handmade Community seem to have, including Odin (the subject of this thread) and Zig. It's not useless but it's a weird niche to target first.

Local variables don't somehow live in this arena allocator in Odin or Zig, and presumably (I haven't used it) not in Jai either. The obvious place for a local to live is the stack - unless you're Java and you need all your user defined types to live on the heap so that they have unique identities. So that's where locals live in Rust, Zig, Odin, C, C#, Go ...