It might be worth mentioning that I'm working on a similar type system for perl5 for quite some time, which is efficient like perl6. In contrast to Moose, which is inefficient and more about the MOP. Types there are only used to slow things down, not to speed it up. All these things were developed around 2002, just forgotten and then partially destroyed with 5.10 and ongoing.

Perl5 hates it, but they haven't seen it and they have generally no idea. It is entirely doable in perl5 only. I got 2-6x speedups in prototypes. But then, perl6 has so much more features worth switching over.