my %set1 = map { $_ => 1 } @array1;
my %set2 = map { $_ => 1 } @array2;

my %intersection = grep $set1{$_}, keys %set2;

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That assumes true values. You're using weird values, so you might have to use exists.

In reply to Re: Using hashes for set operations... by ikegami
in thread Using hashes for set operations... by LanX

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