use strict;
use warnings;

my @var = qw( a b c );
my $ref = \@var;

my %hash;
$hash{$ref} = 1;

foreach (keys %hash) {
   print @$_, "\n";
}

##</code><code>##

Can't use string ("ARRAY(0x225fb8)") as an ARRAY ref while "strict refs" in use