anchor.diff:      [(= (type# x) "string") x]
       [(and (= (type# x) "table")
             (= (get-idx x :tag) "string"))
  -     x]
  +     (get-idx x :value)]
       [:else (pretty x)]))
   
   (defmacro $ (str)
  
positive.code: (import base (defun getmetatable if n progn with for tostring len#
                type# >= > < <= = + - car or and list when set-idx!
                get-idx getmetatable while .. pretty defmacro))
  (import base (concat) :export)
  (import list)
  (import binders (loop let*))
  
negative.code:            (chr (char-at str 1))
             (buf "")]
        [(> i (n str)) (list/push-cdr! sections buf)]
        (let* [((rs re rm) (find (sub str i)
                                 "~%{([^%} ]+)%}"))
               ((is ie im) (find (sub str i)
                                 "%$%{([^%] ]+)%}"))]
          (cond
            [(= rs 1) ; regular ~{foo}
             (progn
               (list/push-cdr! sections buf)
               (list/push-cdr! sections
                               `(display
                                  ,{ :tag "symbol"
                                     :contents rm }))
               (recur (+ i re)
                      (char-at str (+ i re))
                      ""))]
            [(= is 1) ; plain ${foo}
             (progn
               (list/push-cdr! sections buf)
               (list/push-cdr! sections
                               { :tag "symbol"
                                 :contents im })
               (recur (+ i ie)
                      (char-at str (+ i ie))
                      ""))]
            [true (recur (+ 1 i)
                     (char-at str (+ 1 i))
                     (.. buf chr))])))
      `(.. ,@sections)))
  