anchor.diff:      (setf (lambda-information-body form) (cp-form (lambda-information-body form))))
     form)
   
  +(defun mark-as-constant-foldable (name &key (mode t) folder)
  +  (setf (gethash name *constant-fold-modes*) (cons mode folder)))
  +
   ;;; Initialize constant folders.
   (dolist (x '((sys.int::%simple-array-length ((satisfies sys.int::%simple-array-p)))
                (char-code (character))
  
positive.code:              (keywordp (symbol))
               (sys.int::%type-check (t fixnum t))
               (float (t t))))
    (setf (get (first x) 'constant-fold-mode) (second x))
    (when (third x)
      (setf (get (first x) 'constant-folder) (third x))))
  
  (defun mark-as-constant-foldable (name)
    (setf (get name 'constant-fold-mode) t))
  
negative.code: (defun constant-fold (form function arg-list)
    ;; Bail out in case of errors.
    (ignore-errors
      (let* ((info (gethash function *constant-fold-modes*))
             (mode (car info))
             (folder (or (cdr info) function)))
        (etypecase mode
          (cons
           ;; List of arguments & argument types.
  