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:       *true*
        *false*))
  
  (defprimop "set-var!" (*denv* env var value)
    (setf (lookup var (clutter-eval env *denv*)) (clutter-eval value *denv*)))
  
  (defprimop "def-var!" (*denv* env var value)
    (extend (clutter-eval env *denv*) var (clutter-eval value *denv*))
    var)
  
  
negative.code:   (cons x y))
  (defprimfun "cons?" (x)
    (consp x))
  (defprimfun "list?" (x)
    (listp x))
  (defprimfun "car" (cons)
    (car cons))
  (defprimfun "cdr" (cons)
  