Allowing '-' in identifiers: what's the motivation?

[John M. Dlugosz]

E.g. see <http://www.perlmonks.org/?node_id=703265> :

sub bar {
    return 100;
}
sub foo { 50;}
sub foo-bar {
  return  rand(50);
  }
if (foo - bar != foo-bar) {
  print "Haha!\n";
}