What are Declarative and Procedural Macros in Rust?

Explanation & Concept

Macros enable metaprogramming (code that writes code at compile-time): • Declarative Macros (`macro_rules!`): Pattern-matching syntax replacements (e.g. `vec![]`, `println!`). • Procedural Macros: Functions that accept TokenStreams as input and output new TokenStreams (Custom Derive, Attribute, Function-like).

Code Example

rust

// Simple declarative macro
macro_rules! say_hello {
    () => {
        println!("Hello from Rust Macro!");
    };
}

fn main() {
    say_hello!();
}

How It Works & Key Takeaways

Macros expand during compilation before type checking, providing compile-time abstraction without runtime overhead.

Mock Test · 1 Questions · Optional

Ready for Unsafe Rust?

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

Advanced1 questions

Skip

MacrosAdvanced

1Question 1 of 1

rust

What are Declarative and Procedural Macros in Rust?

Explanation & Concept

Code Example

rust

// Simple declarative macro
macro_rules! say_hello {
    () => {
        println!("Hello from Rust Macro!");
    };
}

fn main() {
    say_hello!();
}

How It Works & Key Takeaways

Macros expand during compilation before type checking, providing compile-time abstraction without runtime overhead.

Mock Test · 1 Questions · Optional

Ready for Unsafe Rust?

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

Advanced1 questions

Skip