Just because the old way was deprecated doesn't mean that it wasn't possible to run old and new code next to each other. Also, Perl 5 is a very different examp

Just because the old way was deprecated doesn't mean that it wasn't possible to run old and new code next to each other. Also, Perl 5 is a very different example. While I haven't followed Perl for quite a while, ISTR that Perl had a very similar transition from 4->5 (I personally remember spending a lot of time trying to get old code working on newer OSes). Also, AFAIK but I may be wrong, Perl 6 has not really taken off like Python 3 did.