Associative arrays with void values

[Benji Smith]

dsimcha wrote:
> On the other hand, I'm not sure if it makes sense from a consistency perspective
> to have AAs as a builtin, first class type and sets as a library type.  I'm not
> sure whether this argues more for AAs being a library type or sets being builtin,
> but the inconsistency is just weird.

Especially since an associative array should have a .keys property that 
returns a set.

(Incidentally, I also think the natural set operations, like 
intersection and mutual exclusion, are just as handy for maps as for sets.)

The natural conclusion is that AAs should be library types.

I like the fact that D provides literal syntax for AAs, but I think the 
correct implementation is for the compiler to pass the values from those 
   literal expressions into a library type constructor.

--benji