On Tue, Jun 21, 2011 at 5:24 PM, pipoca
If you were to have your anonymous sum types be a union instead of the disjoint union, then you could say that A :+: A has no meaning. That's what I was originally thinking of when I suggested that syntax. However, as was pointed out to me by David Sankel, disjoint unions are more powerful than regular unions. Since that's the case, Matthew Steele's suggested syntax makes more sense. It means that you need to remember the order of your arguments, but you need to do that with tuples, anyway.
Of course, the same idea could be applied to tuples as well. An "anonymous product" A :*: B would be a collection with no defined order for its elements, indexed by type instead of position. A :*: A would be meaningless for similar reasons to A :+: A. That said, I don't think either retains the tidy algebraic properties that disjoint unions and tuples have, so I'm not sure if calling them sums and products is actually correct. - C.