You can also grep lists for certain 'numbers' of entries (so if you wanted only the items that were in a list twice)
@doubles = grep ++$seen{$_} == 2, @list;

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Jasper

In reply to Re: Re: Perl Idioms Explained - keys %{{map{$_=>1}@list}} by Jasper
in thread Perl Idioms Explained - keys %{{map{$_=>1}@list}} by broquaint

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