How do Iterators work in Rust and why are they zero-cost abstractions?

Explanation & Concept

Iterators in Rust implement the `Iterator` trait with a single `next()` method. Iterator adapters (like `map`, `filter`, `fold`) are compiled down to optimized assembly identical to manual loops, with bounds checks eliminated.

Code Example

rust

fn main() {
    let numbers = vec![1, 2, 3, 4, 5];

    // Lazy iterator chain
    let sum_of_evens: i32 = numbers
        .iter()
        .filter(|&&x| x % 2 == 0)
        .map(|&x| x * x)
        .sum();

    println!("Sum of evens squared: {}", sum_of_evens); // 4 + 16 = 20
}

How It Works & Key Takeaways

Rust iterators produce zero runtime overhead because the compiler flattens and inlines the entire pipeline during optimization.

Mock Test · 1 Questions · Optional

Ready for Enums & Pattern Matching?

Take a quick test to evaluate yourself, or move straight to the next module.

Advanced1 questions

Skip

IteratorsIntermediate

1Question 1 of 1

rust

How do Iterators work in Rust and why are they zero-cost abstractions?

Explanation & Concept

Code Example

rust

fn main() {
    let numbers = vec![1, 2, 3, 4, 5];

    // Lazy iterator chain
    let sum_of_evens: i32 = numbers
        .iter()
        .filter(|&&x| x % 2 == 0)
        .map(|&x| x * x)
        .sum();

    println!("Sum of evens squared: {}", sum_of_evens); // 4 + 16 = 20
}

How It Works & Key Takeaways

Rust iterators produce zero runtime overhead because the compiler flattens and inlines the entire pipeline during optimization.

Mock Test · 1 Questions · Optional

Ready for Enums & Pattern Matching?

Take a quick test to evaluate yourself, or move straight to the next module.

Advanced1 questions

Skip