my @keys = sort your_sorting_routine keys %result;
for my $i (0 .. $#keys - 1) {
    compare($result{ $keys[$i] }, $result{ $keys[$i + 1] });
}

##</code><code>##

my $previous = retrieve_key();
while (defined (my $next = retrieve_key())) {
    compare($result{$previous}, $result{$next});
    $previous = $next;
}