use Modern::Perl;
use Data::Dumper;

	#some ranges, for testing purposes.
my @array = (2,3,4,10,11,12,13,20,21,22,34,35,36,37,38);
my $prev = undef;
my @ranges;
my $index = -1;

	#Build Array of array.
	#One Array ref for each contiguous range
foreach my $val ( sort {$a <=> $b } @array ) 
{

	if (!defined($prev) || $val != $prev +1 ) 
	{
		$index++;
		$ranges[$index] = [$val];
		
	}
	else
	{
		push @{ $ranges[$index] }, $val;
	}
	$prev = $val;
}
print Dumper(\@ranges);


	#loop though each range (array ref), and get the first and last element 
	#for each range
foreach my $a_range (@ranges)
{
	say "range: ", $a_range->[0], '..', $a_range->[-1];
}