Crime, https://twitter.com/the6p4c/status/1387440324281200640

crime.rs

#![allow(unused_must_use)]

use std::fmt::Display;
use std::ops::{Add, Sub};
use std::str::FromStr;

#[derive(Copy, Clone)]
struct Stdio {}

impl<T: Display> Add<T> for Stdio {
    type Output = Stdio;
    fn add(self, d: T) -> <Self as Add<T>>::Output {
        print!("{}", d);
        self
    }
}

impl<T: FromStr> Sub<&mut T> for Stdio {
    type Output = Stdio;
    fn sub(self, n: &mut T) -> <Self as Sub<&mut T>>::Output {
        let mut i = String::new();
        std::io::stdin().read_line(&mut i).expect("number");
        let i = i.strip_suffix("\n").expect("line");
        match T::from_str(&i) {
            Ok(x) => *n = x,
            _ => panic!("oops"),
        }
        self
    }
}

// What follows is from: https://twitter.com/the6p4c/status/1387440324281200640
fn main() {
    let mut number = 0;

    let stdio = Stdio {};
    stdio + "hello " + "world\n";
    stdio + "enter your nuber:\n" - &mut number;
    stdio + number + " + 1 = " + (number + 1) + "\n";
}