How do lifetimes interact with closures

Lifetimes in closures ensure that any references captured by the closure remain valid for as long as the closure itself exists. The compiler infers these lifetimes automatically, but you may need to explicitly annotate them if the closure captures references from multiple sources with different scopes.

fn main() {
    let s = String::from("hello");
    let closure = || println!("{}", s);
    closure();
}

If the closure needs to outlive the scope where the reference was created, you must use the move keyword to transfer ownership into the closure, effectively bypassing lifetime constraints on borrowed data.

A closure is a function that can remember variables from where it was created. Lifetimes are rules that ensure those remembered variables don't disappear while the closure is still trying to use them. Think of it like a librarian checking out a book; the library (closure) can only keep the book (variable) as long as the borrower (the original scope) hasn't asked for it back.