main.rs

#[derive(Debug)]
enum List {
    Cons(Rc<RefCell<i32>>, Rc<List>), Nil
}
 
use crate::List::{Cons, Nil};
use std::cell::RefCell;
use std::rc::Rc;
 
fn main() {
    let val = Rc::new(RefCell::new(5));
 
    let a = Rc::new(Cons(Rc::clone(&val), Rc::new(Nil)));
    let b = Cons(Rc::new(RefCell::new(3)), Rc::clone(&a));
    let c = Cons(Rc::new(RefCell::new(4)), Rc::clone(&a));
 
    *val.borrow_mut() += 10;
 
    println!("a after = {a:?}");
    println!("b after = {b:?}");
    println!("c after = {c:?}");
}