Defining a Simple Closure

Part of the Logic & Flow section of Coddy's Rust journey — lesson 60 of 66.

Now that you understand what closures are, let's learn how to define and use them in your code. The simplest way to create a closure is to assign it to a variable, which allows you to call it later.

Here's how you define a basic closure that takes no parameters:

let my_closure = || {
    println!("Hello from the closure!");
};

Notice the empty vertical bars || - this indicates that the closure takes no arguments. The curly braces contain the code that runs when you call the closure.

To call your closure, you use it just like a function by adding parentheses after the variable name:

let my_closure = || {
    println!("Hello from the closure!");
};

my_closure(); // This calls the closure and prints the message

Challenge

Easy

You will receive a single input containing a message. Create a closure that takes no parameters and prints this message. Store the closure in a variable, then call it to display the message.

Requirements:

Read the input message and trim whitespace
Create a closure using || syntax that prints the message
Store the closure in a variable
Call the closure to execute it

Input:

A single line containing a message (e.g., Welcome to Rust!)

Output:

The message printed by the closure

Cheat sheet

A closure is defined using vertical bars || and can be stored in a variable:

let my_closure = || {
    println!("Hello from the closure!");
};

To call a closure, use parentheses after the variable name:

my_closure(); // Executes the closure

Try it yourself

use std::io;

fn main() {
    // Read input
    let mut message = String::new();
    io::stdin().read_line(&mut message).expect("Failed to read line");
    let message = message.trim();
    
    // TODO: Create a closure that prints the message and store it in a variable
    
    
    // TODO: Call the closure to print the message
    
}