use Digest::MD5 qw(md5_hex);
use strict; 
use warnings;

my $secret = "applepie";

##</code><code>##

sub get_md5 
{
 md5_hex("$secret" . "$_")
};

##</code><code>##

my @array          = qw(foo bar baz);
my %md5_other_hash = (map {&get_md5, $_ } @array);

##</code><code>##

my %md5_hash       = ( &get_md5('foo')  => "foo",
                       &get_md5('bar')  => "bar",
                       &get_md5('bar')  => "baz",
);

##</code><code>##

print &get_md5('foo');