Both your and Errto’s solutions violate your spec: they will ignore duplicate elements in @x, but they report duplicate matches in @y.

The best I’ve come up with that works correctly is 49 characters (or 51 if you care about the context issue).

<Reveal this spoiler or all in this thread>

Makeshifts last the longest.

In reply to Re: Perl Golf-- testing array intersection by Aristotle
in thread Perl Golf-- testing array intersection by BUU

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