Another solution that works with letter ranges as well, without using any regexes:

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

sub human
{
    my (@r, $g, $s, $l);
    while (@_) {
        $l = $g = $s = shift;
        $l = shift while (++$g eq ($_[0] || ''));
        push(@r, $s eq $l ? $s : "$s-$l");
    }
    @r;
}

print join(", ", human(1..12, 14..21, 'aa'..'af', 'zz'..'aaf')), "\n";
print join(", ", human(1, 2, 3, 5, 7, 8, 9, 11, 14)), "\n";

[download]

Output is: 

1-12, 14-21, aa-af, zz-aaf
1-3, 5, 7-9, 11, 14

[download]

update: made work with solo items (thanks CharlesClarkson!)

In reply to Re: Humanized lists of numbers by bikeNomad
in thread Humanized lists of numbers by gryphon

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.