May not be better, faster or stronger. Just a different way to do it. Works w/numbers, letters, and -- as an added bonus -- with strings like aa, ab, ac, ad, af reduced to "aa-ad,af".

sub human {
        my %h;
        @h{@_}=@_;
        $_=join(',',map { $h{$_}?$_:"*" } $_[0]..$_[-1]);
        s/(\w+),(\w+,)*(\w+)/$1-$3/g;
        s/,(\*,)+/,/g;
        split(",");
}
[download]

I'm sure this can be golfed quite a bit, but I'm tired.