3 fn par_for<I, F>(iter: I, f: F)
15 let sum_lengths = Mutex::new(0);
16 par_for(x.windows(4), |x| *sum_lengths.lock().unwrap() += x.len());
18 assert_eq!(*sum_lengths.lock().unwrap(), (x.len() - 3) * 4);
22 let mut elements = [0; 20];
24 // iterators over references into this stack frame
25 par_for(elements.iter_mut().enumerate(), |(i, x)| *x = i as i32);