use strict;
use warnings;

my $rangeStr =
   q{2,10-13,2-5, 7, 32-28,12 , 18 - 23, 31-35};
my %seen = ();

my @expandedRange =
   grep { not $seen{ $_ } ++ }
   map  {
            m{(\d+)\s*-\s*(\d+)}
            ? $2 > $1
              ? $1 .. $2
              : reverse $2 .. $1
            : $_;
        }
   split m{\s*,\s*}, $rangeStr;

print qq{@expandedRange\n};