Implement destructuring-bind

[hrs]

It'd be slick if we could perform a destructuring-bind when binding variables. Something like:

(destructuring-bind (a (b c) d) '(1 (2 3) 4)
    (list a b c d)) # => '(1 2 3 4)

I think §18 of On Lisp has some good stuff on destructuring. We could probably implement this as a macro in the standard library.

[hrs]

We might also think about building a more general pattern-matching system, like:

(match some-expression
  ((a (a b) . rest) (do-something a b))
  (else (do-something-else some-expression)))

We could also do destructuring in function definitions, let blocks, etc.

Maybe these are all special cases of a more general Binder?

[hrs]

Racket also has a terrific-looking library for pattern matching. Maybe we should check it out for inspiration?

[hrs]

On second thought, while I think full-blown argument-list pattern-matching would be pretty cool, that's a whole separate issue that Blueprint might never implement. Let's keep this issue scoped to just implementing a destructuring-bind macro.