Rust Macros — Declarative Macros with macro_rules! and Procedural Macros

DodaTech Updated 2026-06-28 1 min read

In this tutorial, you will learn about Rust Macros. We cover key concepts, practical examples, and best practices to help you master this topic.

Rust macros include declarative macro_rules! for pattern-based Code Generation and procedural macros for custom derive, attribute, and function-like macros.

What You'll Learn

macro_rules! basics
Pattern matching in macros
Repetition in macros
Procedural macros overview

Why It Matters

Macros reduce boilerplate. DodaZIP uses macros for error handling patterns. Serde's derive macros are procedural macros.

Real-World Use

Code generation, boilerplate reduction, DSL creation, test utilities.

// Declarative macro
macro_rules! create_function {
    ($func_name:ident) => {
        fn $func_name() {
            println!("Called {}", stringify!($func_name));
        }
    };
}

create_function!(foo);
create_function!(bar);

// Macro with repetition
macro_rules! vec_of_strings {
    ($($x:expr),*) => {
        {
            let mut v = Vec::new();
            $(v.push($x.to_string());)*
            v
        }
    };
}

macro_rules! assert_equal {
    ($left:expr, $right:expr) => {
        assert_eq!($left, $right, "{} != {}",
            stringify!($left), stringify!($right))
    };
}

// Macro for building
macro_rules! hashmap {
    ($($key:expr => $value:expr),* $(,)?) => {
        {
            let mut map = std::collections::HashMap::new();
            $(map.insert($key, $value);)*
            map
        }
    };
}

fn main() {
    foo();
    bar();

    let v = vec_of_strings!("a", "b", "c");
    println!("{:?}", v);

    assert_equal!(2 + 2, 4);

    let map = hashmap!("a" => 1, "b" => 2);
    println!("{:?}", map);
}

← Previous Rust Traits Advanced — Associated Types, Default Generic Parameters, and Supertraits Next → Rust Unsafe Code — Unsafe Blocks, Raw Pointers, and FFI with C Code

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