Concurrency-enabled mechanisms for sharing mutable and/or immutable state between tasks.

Example

In this example, a large vector of floats is shared between several tasks. With simple pipes, without Arc, a copy would have to be made for each task.

extern mod std;
use extra::arc;
let numbers=vec::from_fn(100, |ind| (ind as float)*rand::random());
let shared_numbers=arc::Arc::new(numbers);

  do 10.times {
      let (port, chan)  = stream();
      chan.send(shared_numbers.clone());

      do spawn {
          let shared_numbers=port.recv();
          let local_numbers=shared_numbers.get();

          // Work with the local numbers
      }
  }