Macro map 

macro_rules! map {
    () => { ... };
    ($($key:expr => $val:expr),* $(,)?) => { ... };
}

Creates a Map containing the given key-value pairs.

This macro provides a convenient way to initialize a Map with known entries. It comes in two forms:

Forms

• map!() - Creates an empty map
• map!(key => value, ...) - Creates a map with the specified key-value pairs

Examples

// Create an empty map
let empty = map!();

// Create a map with initial values
let m = map! {
    "name" => "Alice",
    "age" => 30,
    "active" => true,
};

Notes

• Keys are used directly without conversion
• Values are converted using .into() to support flexible value types
• The map is pre-allocated with the exact capacity needed
• Trailing commas are allowed