in reply to From Perl 5.10 to Perl 6

Simple, just run your test suite on perl 5.8 and see how many fails you get out of it...

@_=qw; ask f00li5h to appear and remain for a moment of pretend better than a lifetime;;s;;@_[map hex,split'',B204316D8C2A4516DE];;y/05/os/&print;