++$i, --$j

Yes, that's a good example.

However, it seems that as long as the sub-expressions are evaluated, it would work the same way:

for (my ($i, $j) = (1, 5); $i <= 5; ++$i + --$j) {
    say abs($i - $j); 
}

4
2
0
2
4
[download]

Which is a bit more unobvious, and not what I was after.

A do { block; } also works, as would almost anything that evaluated the sub-expressions, and throw the result away. A more complicated variable update would look odd though. Probably better to just use a while loop in that case.

Are there any other examples that are more difficult to rewrite without the comma operator?