Pattern matched assignment

[dgkf]

I would love for R to support some sort of destructuring.

Specifically, I think it would look something like this:

list(a, b) <- list(1, 2)

Or, since we already support (, ) syntax as a list, this could be rewritten as:

(a, b) <- (1, 2)

Since R already implements generic assignment calls, this would mean that we'd just have a couple special cases for some basic AST constructors.