use strict;
use warnings;
use Digest::MD5 qw( md5 );

my @a1 = ( 'aa', 'a', '' );
print '[', join( '|', @a1 ), "]\n";
my $d1 = md5( @a1 );

my @sorted_a1 = sort @a1;
print '[', join( '|', @sorted_a1 ), "]\n";
my $sorted_d1 = md5( @sorted_a1 );

printf( "Digests are %s\n",
        ( $d1 eq $sorted_d1 ) ? 'equal' : 'unequal' );

##</code><code>##

[aa|a|]
[|a|aa]
Digests are equal