Re:

I assumed that Perl 6 has some sort of type system, and it is approved at some level. So it didn't occur to me to read it as 'this paper is a proposal to change the Perl 6 type system.'

It's worse than that. If you grep the synopses, you'll find,

• Perl 6 has an optional type system that helps you write safer code that performs better. The compiler is free to infer what type information it can from the types you supply, but will not complain about missing type information unless you ask it to.
• A variable's type is a constraint indicating what sorts of values the variable may contain. More precisely, it's a promise that the object or objects contained in the variable are capable of responding to the methods of the indicated "role".
• Junction types

It is vague at best, with some interesting clues of requirements. It has not yet been designed, just talked about in the newsgroup.

Thanks for the other suggestions.

Do you have any code for quartnion I could rewrite in Perl 6 as the example?

—John