Code shared from the Rust Playground

playground.rs

use std::fmt::Display;
use std::ops::FnMut;

fn main() {
    let a: u64 = 1.cast();
    let b: u16 = 1.cast();
    let mut v: Vec<&dyn Display> = Vec::new();
    v.push(&true);
    
    let mut cl = gen_counter(1);
    cl();
    let n = cl();
    println!("{}", n);
}

fn gen_counter(init: i32) -> impl FnMut() -> i32 {
    let mut n = init;
    move || {
        let ret = n;
        n += 1;
        ret
    }
}

trait As<T> {
    fn cast(self) -> T;
}

impl As<u64> for u8 {
    fn cast(self) -> u64 {
        self as u64
    }
}

impl As<u16> for u8 {
    fn cast(self) -> u16 {
        self as u16
    }
}