Re: A sort of perl golf challenge

Got it. This one’s in fact even shorter, heh.

sub collapse {
my $str = join ', ', @_;
$str =~ s/(\d+)(?:, ((??{$^N + 1})))+/$1-$^N/g;
return $str;
}

But I just noticed it’s buggy without the \b assertions your initial attempt had:

sub collapse {
my $str = join ', ', @_;
$str =~ s/\b(\d+)(?:, ((??{$^N + 1})\b))+/$1-$^N/g;
return $str;
}

PS.: it would be nice if tags were permitted in comments…