Simple rust program which deals with file reads in 3 different ways

main.rs

// This program will read test.txt file and print it line by line
// implemented in 3 different ways

use std::io::BufReader;
use std::io::BufRead;
use std::fs::File;

fn main() {

    // Procedural
    let f = File::open("test.txt").unwrap();
    let file = BufReader::new(&f);

    for line in file.lines() {
        let l = line.unwrap();
        println!("{}", l);
    }

    // Pattern matching
    match File::open("test.txt") {
        Ok(f) => {
            let file = BufReader::new(&f);
            for line in file.lines() {
                match line {
                    Ok(l) => {
                        println!("{}", l);
                    }
                    Err(e) => {
                        println!("{}", e);
                    }
                }
            }
        }
        Err(e) => {
            println!("{}", e);
        }
    };

    // Monad
    File::open("test.txt")
        .and_then(|f| BufReader::new(f).lines().into_iter().collect::<Result<Vec<std::string::String>, std::io::Error>>())
        .map(|lines| {
            for l in lines {
                println!("{}", l);
            };
        }).unwrap();
}

test.txt

Hello
World
!!!!!