Better?
If that worked, it wouldn't be semantically the same as Aristotle's, Zaxo's, or my reply. Nor of the perlfaq or tachyon's (which show a difference of both arrays).

Did you test your code? It is a nice thought, however, I cannot make that work on 5.6.1, 5.8.1, or 5.8.5
For a simple array of int's @diff is always undef.
For an array containing scalars I get "Invalid range in regex" error, which is what I expect.

-xtype