BitArray.opApply

bool[] ba = [1,0,1];

auto a = BitArray(ba);

int i;
foreach (b;a)
{
    switch (i)
    {
        case 0: assert(b == true); break;
        case 1: assert(b == false); break;
        case 2: assert(b == true); break;
        default: assert(0);
    }
    i++;
}

foreach (j,b;a)
{
    switch (j)
    {
        case 0: assert(b == true); break;
        case 1: assert(b == false); break;
        case 2: assert(b == true); break;
        default: assert(0);
    }
}