TIL that Rust supports inline struct definitions! https://github.com/rust-lang/rust/commit/6d43225bfb08ec91f7476b76c7fec632c4a096ef#diff-1dfa77331261e81c069657949febee032512a702bfe5865d7993cfc9f577f2f3
They still need names, but it allows you to define structs only used in a single function.