// Trying to learn closures/procs in Rust // Want to capture a variable whose private state I can mutate // Currently failing

proc.rs

//
// Trying to learn closures/procs in Rust
// Want to capture a variable whose private state I can mutate
//
fn main() {
    fn call_proc(b: proc(u64) -> u64) {
        let x = b(10u64);
        println!("{:?}", x);
    }
    
    let p = get_proc();
    call_proc(p);
    call_proc(p);  // error: use of moved value: `p`
    // compiler note: `p` moved here because it has type `proc:Send(u64) -> u64`, 
    //                 which is non-copyable (perhaps you meant to use clone()?)
}

fn get_proc() -> proc(u64) -> u64 {
    let count: ~u64 = ~0;
    proc(N: u64) -> u64 {
        let mut counter = count;
        let val: u64 = N + *counter;
        *counter += 1;              
        return val;
    }
}