I dislike this idea, mostly because the syntax is pretty trivial anyway using the bracket currying suggested elsewhere. [map car] isn't much shorter than $car, and it's much more flexible and leaves $ (or whatever symbol might end up being used) open for some other meaning. It's also more explicit, although I'm not sure that's worth much.
That's not necessarily true; as I pointed out further down (http://arclanguage.org/item?id=4704), you can get the effect you want. On the other hand, you do take a speed hit. I'm inclined towards supporting both, but swapping the args is very easy to write and may not belong in the core.
