http://qs1969.pair.com?node_id=44096

This snippet shows how to use an expression as an lvalue. It's based on something my boss said you could only do in Algol68.
($a,$b) = (0,1); ($a < $b ? $a : $b) = $a+$b for (1..$n); print $n%2 ? $a : $b, "\n"