How would I parallelize this?

gistfile1.txt

use std::io::timer;
use std::time::Duration;
use std::sync::Future;

trait Constraint {
    fn is_satisfied(&self) -> bool;
}
#[deriving(Send)]
struct Foo { name: &'static str, a: bool, b: bool }
#[deriving(Send)]
struct Bar { name: &'static str, a: bool }

impl Constraint for Foo {
    fn is_satisfied(&self) -> bool {
        let res = self.a && self.b;
        timer::sleep(Duration::seconds(2));
        println!("{} is {}",self.name,res); 
        res
    }
}
impl Constraint for Bar {
    fn is_satisfied(&self) -> bool {
        let res = self.a;
        println!("{} is {}",self.name,res); 
        res
    }
}

fn main(){
    let mut cs: Vec<Box<Constraint>> = Vec::with_capacity(10);
    cs.push(box Foo {name: "c1",a: true,b: true} as Box<Constraint>);
    cs.push(box Foo {name: "c2",a: true,b: true} as Box<Constraint>);
    cs.push(box Foo {name: "c3",a: true,b: true} as Box<Constraint>);
    cs.push(box Bar {name: "c4",a: true} as Box<Constraint>);
    cs.push(box Bar {name: "c5",a: false} as Box<Constraint>);
    cs.push(box Foo {name: "c6",a: true,b: true} as Box<Constraint>);
    cs.push(box Foo {name: "c7",a: true,b: true} as Box<Constraint>);
    cs.push(box Bar {name: "c8",a: true} as Box<Constraint>);
    cs.push(box Bar {name: "c9",a: true} as Box<Constraint>);
    cs.push(box Foo {name: "c10",a: true,b: true} as Box<Constraint>);
    let slow_serial = cs.iter().all(|x| x.is_satisfied());
    // following does not work 
    // error: cannot capture variable of type `&Box<Constraint:'static+Send>`, which does not fulfill `'static+Send`, in a bounded closure
    // let slow_parallel_tasks = cs.iter().map(|x| Future::spawn(proc() { x.is_satisfied() }));
}