anchor.diff:        [true (error (.. "unsupported pattern " (pretty pattern)))])))
   
   
  -(defun compile-pattern (pattern symb body)
  +(defun compile-pattern (pattern symb body) :hidden
     `(if ,(compile-pattern-test pattern symb)
        (let* ,(compile-pattern-bindings pattern symb)
          ,@body)
  
positive.code: (import table (struct))
  (import string (.. char-at sub))
  
  (defun cons-pattern? (pattern)
    (eq? (nth pattern (- (# pattern) 1)) '.))
  
  (defun cons-pat-left-side (pattern)
    (slice pattern 1 (- (# pattern) 2)))
  
  (defun cons-pat-right-side (pattern)
    (last pattern))
  
  (defun meta? (symbol)
    (and (symbol? symbol)
         (eq? (char-at (get-idx symbol "contents") 1) "?")))
  
  (defun compile-pattern-test (pattern symb)
    (cond
      [(list? pattern)
       (cond
  
negative.code:      `(eq? ,symb ,pattern)]
      [true (error (.. "unsupported pattern " (pretty pattern)))]))
  
  (defun compile-pattern-bindings (pattern symb) :hidden
    (filter (lambda (x) (/= (# x) 0))
      (cond
        [(list? pattern)
  