anchor.diff:  (defprimfun "eval" (expression environment)
     (clutter-eval expression environment))
   
  -(defprimop "lookup" (*denv* symbol environment)
  -  (lookup symbol (clutter-eval environment *denv*)))
  -
  -(defprimop "set-lookup!" (*denv* value symbol environment)
  -  (setf (lookup symbol (clutter-eval environment *denv*)) (clutter-eval value *denv*)))
  -
  -(defprimop "def-lookup!" (*denv* value symbol environment)
  -  (extend (clutter-eval environment *denv*) symbol (clutter-eval value *denv*)))
  -
  -(defprimfun "gensym" (name)
  -  (clutter-symbol name nil))
  -
   (defprimfun "make-env" (&rest parents)
     (apply #'make-env parents))
   
  
positive.code:   (apply #'list* values))
  (defprimfun "length" (seq)
    (length seq))
  ;;; TODO: Does this sideffect?
  (defprimfun "append" (&rest lists)
    (apply #'append lists))
  
  (defprimfun "set-head" (cons new-car)
    (rplaca cons new-car))
  (defprimfun "set-tail" (cons new-cdr)
    (rplacd cons new-cdr))
  
  (defprimfun "eql?" (x y)
    (if (eql x y) *true* *false*))
  
  (defprimfun "symbol?" (x)
    (if (clutter-symbol-p x) *true* *false*))
  
negative.code:   (cons x y))
  (defprimfun "cons?" (x)
    (consp x))
  (defprimfun "list?" (x)
    (listp x))
  (defprimfun "car" (cons)
    (car cons))
  (defprimfun "cdr" (cons)
  