Pass reference of read-only vector to thread

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• Arc allows us to have reference counting.
• Here the clone only copies the reference and not the whole data structure.

examples/threads/pass-reference-to-vector/src/main.rs

use std::sync::Arc;

fn main() {
    let animals = Arc::new(Vec::from_iter(["mouse", "elephant", "cat", "dog", "giraffe"].map(|animal| animal.to_string())));
    println!("{:?}", animals);
    {
        let animals = animals.clone();
        let handle = std::thread::spawn(move || {
            list_animals(&animals);
        });
        handle.join().unwrap();

    }
    println!("{:?}", animals);
}

fn list_animals(animals: &Vec<String>) {
    for animal in animals {
        println!("{}", animal);
    }
}