The new invariant.

[Chris Nicholson-Sauls]

A couple of quick questions about the upcoming 'invariant' type constructor.  Given a 
class Foo, will there be a way to mark the class as having only invariant instances?  Ie 
can I declare it as 'invariant class Foo {}' much as 'scope class Foo {}' would make it 
RAII-only?

Second, say I want to make an associative array of invariant Foo instances.  How would I 
declare this?  (Let's use int as the key type, for simplicity.)
invariant Foo[int] pool ; // reads to me as the AA type is invariant, which is useless
invariant(Foo)[int] pool ; // perhaps?  like with the new const()?

This would be quite nifty for one of my projects, if it works like I expect.

private static invariant(Symbol)[invariant(char[])] pool ;

It'd be beautiful.  Though I still worry a little about the current invariant{} contract 
being broken.

-- Chris Nicholson-Sauls