I would think it could work the same way the $_ variable works in nested loops...

Ah, you mean, "$_ is the default iterator value, but it's easily replaced by another variable"? How should that work for the loop counter?

Right...I think. If I need to use the value of $_ in a nested loop, I'd just assign it to another variable:

for (0 .. 10) {
    my $outer_elem = $_;
    for (0 .. 20) {
        my $inner_elem = $_;

        do_something($outer_elem, $inner_elem);
    }
}

# Yeah, I know doing this is better:
for my $outer_elem (0 .. 10) {
    for my $inner_elem (0 .. 20) {
        do_something($outer_elem, $inner_elem);
    }
}
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So I guess the loop counter would just keep a count of the most immediate loop it's in. I don't really know--this is all just how I would expect such a variable to work (if it existed).

So if we pretend $. is the loop counter:

foreach my $elem1 (@array1) {
    my $outer_idx = $.;
    foreach my $elem2 (@array2) {
        my $inner_idx = $.;
        
        # Blablabla...
    }
}
[download]

I should emphasize: I'm not pushing for this to become a feature or anything. I was just curious if there was anything like this (and this is how I would imagine it might work if there was).