anchor.diff:  (defparameter *actions* (seq))
   
   ;; functions
  -(defun done? (future)
  +(defun done-p (future)
     (slot-boundp future 'val))
   
   (defun make-future ()
  
positive.code: 
  (defun/cc wait-for (future)
    (let/cc continuation
      (if (not (done? future))
        (setf (completed-cb future) continuation)
        (funcall continuation)))
    (val future))
  
negative.code:                 #:less-first)
    (:export #:future
             #:ident
             #:done-p
             #:register-future
             #:complete-future
             #:make-future
  