> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt. # Functions Make required ownership and failure behavior visible in the signature. ## Contracts ### Why A borrowed string communicates that reading it does not require ownership of its allocation. ### Rules - MUST use named `fn` declarations for reusable operations. \[review] - MUST annotate public return types and express expected failure with Result. \[review] - MUST accept `&str` and slices when ownership is not required. \[review] - MUST take owned values only when the operation retains or consumes them. \[review] - MUST use a named input struct when several parameters form one domain request. \[review] - MUST keep each operation focused on one responsibility. \[review] - MAY use closures as iterator callbacks or injected capabilities. \[review] ## Example ```rust pub fn total_lengths(names: &[&str]) -> usize { names.iter().map(|name| name.len()).sum() } #[test] fn counts_borrowed_names() { assert_eq!(total_lengths(&["docs", "code"]), 8); } ``` \[review] The compiler and tests check signature use. Review checks ownership decisions and operation scope. ## Enforcement The compiler and tests check signature use. Review checks ownership decisions and operation scope.