Explain iterators in Rust and their lazy evaluation.

Iterators in Rust: • Lazy evaluation - no work until consumed • Iterator trait with next() method • Adapters transform iterators • Consumers execute the iterator • Zero-cost abstractions Example: let v = vec![1, 2, 3, 4, 5]; // Lazy - no work done yet let iter = v.iter() .map(|x| x * 2) .filter(|&x| x > 4); // Consumer - work is done here let results: Vec = iter.collect(); // Chain operations let sum: i32 = v.iter().map(|x| x * x).sum();