I just tested this with Data::Compare. To use the Compare function, all that is required is appending the Compare sub contents from the Data::Compare source into the script following this required code (note that both Carp and Scalar::Util have been in core since pre-5.8).

use warnings;
use strict;

use Carp;
use Scalar::Util;

my (%been_there, %handler);

print Compare([], [qw(1 2)]);
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