The problem with your suggestion is that two arrays with the same elements will give two entries in the hash (because they will have different references). Consider:

use strict;
use warnings;
use Data::Dumper;

my @foo = qw/1 2 3 4 5 6/;
my @fu  = qw/1 2 3 4 5 6/;
my %bar = (
           \@foo => 'elephants',
           \@fu  => 'zebras'
        );

print Dumper \%bar;
[download]

Outputs something like:

$VAR1 = {
          'ARRAY(0x18ae770)' => 'zebras',
          'ARRAY(0x17f0ec8)' => 'elephants'
        };
[download]

And:

my @foo = qw/1 2 3 4 5 6/;
my @fu  = qw/1 2 3 4 5 6/;
my %bar = (
           join ('',@foo) => 'elephants',
           join ('',@fu)  => 'zebras'
        );

print Dumper \%bar;
[download]

Outputs:

$VAR1 = {
          '123456' => 'zebras'
        };
[download]