aggregate contiguous positive numbers

aggregate.pl

use strict;
use warnings;
my @n;
while (<>) {
  push @n, $_;
}

my $first_num = 0;
my $next_num = 0;
my $contig = 0;
my $last_num = 0;
push @n, -1;
while (1) {
  my $n = shift @n;
  $n || last;
  chomp $n;
  # initialize
  unless ($next_num) {
    $contig = 0;
    $first_num = $n;
    $next_num = $n + 1;
    $last_num = $n;
    next;
  }
  if ($n == $next_num) {
    $contig = 1;
    $last_num = $n;
    $next_num = $n + 1;
    next;
  } elsif ($contig == 1) {
    print "$first_num-$last_num\n";
    # reinit
    $next_num = 0;
    unshift @n, $n;
    next;
  }
  # no contig, just last number and unshift or end
  print "$last_num\n";
  # hit the end?
  last if $n == -1;
  # reinit
  $next_num = 0;
  unshift @n, $n;
}

deaggregate.pl

while (<>) {
  unless (m/-/) {
    print "$_";
    next;
  }
  m/(\d+)-(\d+)/;
  for ($1..$2) {
    print "$_\n";
  }
}