In Rust programming, memory safety is not a suggestion—it’s a guarantee. The language enforces strict ownership and borrowing rules that eliminate entire classes of bugs common in other systems languages. But as Rust developers push the boundaries of performance and abstraction, one concept often sparks curiosity and confusion alike: non-lexical lifetimes (NLL).
What Are Lifetimes?
In Rust, a lifetime is the scope during which a reference is valid. It ensures that data referenced by a variable lives long enough to be safely accessed, preventing dangling pointers and data races. Traditionally, Rust’s compiler used lexical lifetimes—meaning lifetimes were tied strictly to the scope structure of your code.