#!/usr/bin/perl -w
use strict;

sub list2ranges {
	my @list = sort {$a<=>$b} @_;
	my $current = $list[0];
	my @ranges = ($current) ;
	for (my $i=1;$i <= @list; $i++){
		if ($list[$i] && $list[$i] - $current == 1 || $list[$i] && $list[$i] - $current < 1  && substr($list[$i],0,-1) eq substr($current,0,-1) ){
			$current = $list[$i];
		}
		else{
		  	$ranges[-1] .= " - $current" if $ranges[-1] != $current;
		  	$list[$i] && push @ranges, $current = "$list[$i]" ;
		}
	}

	return wantarray ? @ranges : join(", ",@ranges);
}

# Examples
my @test = (qw( 01 2 3), 5, (7..9), (11..12), (17..19), 20, 30, qw(30.1 30.2 30.33 30.34 30.35));
my @ranged = list2ranges(@test);

print join(", ",@test)," \n";
print join(", ",@ranged)," \n";
print scalar(list2ranges(@test)),"\n";