newLISP the true champion of homoiconicity

Can your Lisp do this, /prog/?

(define (plus-minus a b)
  (begin
    (setf (nth '(1 2 0) plus-minus) (if (= (nth '(1 2 0) plus-minus) -) + -))
    (+ a b)))

(plus-minus 10 2)
8
(plus-minus 10 2)
12

newLISP treats code literally as data unlike Common Lisp or Scheme.

>>37

Making them explicit helps with efficiency in the implementation. To maintain performance, they should all be expanded at compile time, and this would be hard if they weren't explicit. Not to mention a macro getting into a place where you only wanted a function would be a hard bug to figure out. But like all things that help performance, it must also cut down on expressive power and possibilities.