There's a few ways to implement your own Sets right now, if
needed. You found one way (using the built in AAs), but that's
not all.
* You could use Array!bool (which efficiently stores bools) to
store whether integers are in or out of your set.
* You can use std.container's redBlackTree to make a set which
would work better if your items are objects or you're dealing
with a sparse array.
There's probably a few other extremely simple methods, but those
are the two I had on the top of my head. I'm not really sure
having a particular "Set" in the library would be all that
useful. Generally, if I want a set, I have a particular idea of
how one should be implemented for my particular data.
