You need something external to the loop to keep the state.

You could use a combination of the address of the calling opcode as a key to get the appropriate state, but you'd have no way to reset to the counter if you did that, so you wouldn't be able to last/return/die from within the loop.

Just look at each for example. To properly use each, you need to do: 

keys %hash;  # Reset iterator
while (my ($k, $v) = each(%hash)) { ... }

[download]

And even then, it doesn't nest because the iterator is per-hash, not per-each.

In reply to Re^3: Designing a DWIMish interface for generator function by ikegami
in thread Designing a DWIMish interface for generator function by LanX

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