arcs.rs

extern mod extra;
use extra::arc::Arc;

fn main() {
    let x = ~5;
    let y = Arc::new(x); // x is no longer pointer to ~5, and y points to the pointer x was that is not to the value but the 
                         // but the pointer x held. 
    let z = y.clone();  // same semantics, the clone produces a pointer to the pointer x was. 

    println!("{}", **(y.get())); // see we have that double reference we have to deref twice.
    println!("{}", **(z.get()));
}

I figured out the double ref thing from the compiler in that y.get() complained about can't find default format implementation for &~int, adding one asterisk reported ~int, and double compiled.