> I believe "no" was the word for which you were reaching? (Possibly "not
That depends on what the OP want. The design of Perl 6 definitely have backward compatibility addressed, at least so long as Perl extension module is not involved (i.e., there is no C code involved). The Perl 6 is designed to be based on a virtual machine (Parrot) that can interpret many different languages, Perl 5 is one of them. Then the Parrot engine can run many back-end languages at the same time, with objects of different languages cooperating in a fashion similar to Java dynamic language interface. Finally, the Perl 6 language is designed so that modules are distinguishable from Perl 5 modules by just looking at the first few tokens, so that the eventual VM can load a module and decide whether to use Perl 5 or Perl 6 back-end automatically. So the design is there, it's just an issue about when it actually enters implementation.