Functions: Structural Dispatch

Functions are the core building blocks of execution in Rust. They are declared using the fn keyword.

Type Safety Features

• Explicit Signatures: Unlike variables where types are frequently inferred, function parameters and return types must be declared explicitly. This keeps code contracts clear and facilitates fast compiler type checking.
• Return Expression: Functions return the value of the final expression in their block. Omit the semicolon to treat a line as an expression.

// Standard function emitting keyboard stroke
fn send_stroke(key_code: u32) {
    println!("Emitting virtual key event: {}", key_code);
}

Diverging Functions (!)

Functions that never return (e.g., executing infinite OS message loop processes) return the special "never" type !.

fn event_loop() -> ! {
    loop {
        poll_input_hooks();
    }
}