This code doesn't interpolate but it parses your input into something NetAddr::IP might agree with...:

my $range = shift @ARGV; # E.g. 10.0.10-20.0

if ($range =~ /([0-9\.]+)\-([0-9\.]+)/) {
  my $begin = $1;
  my $end = $2;
  my @begin_quad = split(/\./, $begin);
  my @end_quad = split(/\./, $end);
  push @begin_quad, 0 while @begin_quad < 4;
  my $index = 0;
  while (@end_quad < 4) {
    unshift @end_quad, $begin_quad[$index];
    $index;
  }
  print "Begin: ".join('.', @begin_quad)."\n";
  print "End: ".join('.', @end_quad)."\n";
} else {
  die "Expected a range";
}

exit;
[download]