anchor.diff:          (dolist (el arr)
             (setf (aref arr idx) (fn el))
             (setf idx (1+ idx))))
  -      (return arr))
  +      arr)
   
       (defun map (fn arr)
         "Call FN on each element in ARR and return the returned values in a new array."
  
positive.code:             (dolist (element (aref arrs 0))
                ((@ result-array push) (fun element)))
              (dotimes (i (length (aref arrs 0)))
                (let ((args-array (mapcar (lambda (a) (return (aref a i))) arrs)))
                  ((@ result-array push) ((@ fun apply) fun args-array)))))
          (return result-array)))
  
      (defun map-into (fn arr)
        "Call FN on each element in ARR, replace element with the return value."
  
negative.code:           (unless (member el arr-to-sub)
              (setf (aref result idx) el)
              (setf idx (1+ idx))))
          result))
  
      (defun reduce (func list &optional init) ;; the use of init here is actually a bit broken wrt null
        (let* ((acc))
          (do* ((i (if init -1 0) (1+ i))
                (acc (if init init (elt list 0)) (func acc (elt list i))))
               ((>= i (1- (length list)))))
          acc))
  
      (defun nconc (arr &rest arrs)
      (when (and arr (> (length arr) 0))
  