in reply to Re^3: Mini-Tutorial: Working with Odd/Even Elements
in thread Mini-Tutorial: Working with Odd/Even Elements

It's not a problem with map_pairs. You'll notice the same with map and for.

Hash keys aren't Perl variables (aren't an SV), so %hash can't possibly return an alias to them. It returns a copy.

It could return something magical that would result in the keys being "changed", but it doesn't. One could make a tie implementation if one needed such a feature.