What if _ was a list in the event that the function was passed more than one argument? With the . syntax, you could use _.1, _.2 for an arbitrary number of arguments, and wouldn't have to introduce __ to access the list of arguments.
Hmmm, I like that. The only problem is that then you can't just say _ to access the first argument, and one-argument functions are the most common case. So you'd either need a new name for _ or a different name for the list, it seems to me, and those break symmetry.
The UI language features a great deal more separation of code and design than the arc web framework. I know libraries aren't a high priority at the moment, but this guys UI is pretty expressive. To be honest, I wasn't expecting much from the demo app, but it had a very rich presentation layer, and his actual code was very simple.
To me, this code is illustrating that "." and "!" should have their meanings reversed. "b!l" and "b!r" in arc would map to "b.l" or "b.r" in python, while "b.side" in arc, is something more akin to "b.getattr(side)"
Ofcourse, swapping the meanings of ! and . puts a cramp in syntax like "b.0"...
Yeah, it was a deliberate design decision by Macromedia. They wanted to keep the VM small, so they deliberately left out anything that smacked of a runtime compiler. Eval, regexps. Though I heard regexps may have come back in AS3...