Concurrency and a useful CLI

In plain English

Threads, channels and async runtimes each solve different problems. Use std::thread for CPU work and message passing for ownership transfer. A CLI should parse arguments, return meaningful exit codes and print errors to stderr.

use std::sync::mpsc;
use std::thread;

fn main() {
    let (tx, rx) = mpsc::channel();

    thread::spawn(move || {
        tx.send("finished").unwrap();
    });

    println!("{}", rx.recv().unwrap());
}