[ugexe]

What Perl6 rewrite? Perl6 is a specification. Are you referring to various compilers that have been implemented over the years as rewrites?

[cygx]

What Perl6 rewrite?

The rewrite of the language.

It was decided that if you need to break backwards compatibility anyway, you might as well do so in a big way. In contrast, Python3 breaks backwards compatibility as well, but only offers moderate improvements.