Consider loop:

for (uint i = 0; i < array.length; i++) {
    array[i] = 0;
}

One could turn it into (syntax assume similar extensions as one in bug #638199):

foreach (ref var el in array) {
    var = 0;
}

Proposed solution:

 - For arrays it treats the iteration variable as pointer as if in ref argument
 - For  iterators it would call set function if it exists for store
 - For "lists" syntax it would call set function if it exists for store
 - (see proposed solution for bug #645850) For functional iteration I can add virtual function to ListIterator