sub split_sort {
  my ($in_a, $in_b, $split, $sort_type) = @_;
  $split = qr($split);

  my ($numa1, $numa2) = split(/$split/, $in_a);
  my ($numb1, $numb2) = split(/$split/, $in_b);

  if ($sort_type =~ /^num/) {
    $numa1 <=> $numb1 || $numa2 <=> $numb2
  }
  elsif ($sort_type =~ /^(alpha|letter)/) {
    $numa1 cmp $numb1 || $numa2 cmp $numb2
  }
}

##</code><code>##

  my @numbers = qw(1:2 1:02 3:4 5:78 50:89 10:5);

  my @sorted = sort @numbers;
  # The list as it is written can not be sorted as numbers.
  # returns
  # [
  #   '10:5',
  #   '1:02',
  #   '1:2',
  #   '3:4',
  #   '50:89',
  #   '5:78'
  # ]

  my @split_sorted = sort { split_sort($a, $b, ':', 'number') } @numbers;
  # returns
  # [
  #   '1:2',
  #   '1:02',
  #   '3:4',
  #   '5:78',
  #   '10:5',
  #   '50:89'
  # ];