anchor.diff:     :parent nil
      :bindings
      (alist-hash-table 
  -    (list (cons '+ (make-clutter-operator
  -                    :function (lambda (*denv* values)
  -                                (reduce #'+ (mapcar (rcurry #'clutter-eval *denv*)
  -                                                    values)))))
  -          (cons 'car (make-clutter-operator
  -                      :function (lambda (*denv* values)
  -                                  (car (clutter-eval (car values) *denv*)))))
  +    (list (cons '+
  +                (make-function
  +                 (make-clutter-operator
  +                  :function (lambda (*denv* values)
  +                              (reduce #'+ values)))))
  +          (cons 'car
  +                (make-function
  +                 (make-clutter-operator
  +                  :function (lambda (*denv* values)
  +                              (caar values)))))
  +          (cons 'cdr
  +                (make-function
  +                 (make-clutter-operator
  +                  :function (lambda (*denv* values)
  +                              (cadr values)))))
  +          (cons 'list (make-function
  +                       (make-clutter-operator
  +                        :function (lambda (*denv* values)
  +                                    values))))
  +          (cons 'list* (make-function
  +                        (make-clutter-operator
  +                         :function (lambda (*denv* values)
  +                                     (apply #'list* values)))))
             (cons 'eval (make-clutter-operator
                          :function (lambda (*denv* values)
                                      (let ((values (mapcar (rcurry #'clutter-eval *denv*)
  
positive.code: 
  (defun eval/combiner (expression env)
    (let ((f (clutter-eval (car expression) env)))
      (if (clutter-operator-p f)
          (invoke f env (cdr expression))
          (error "Not an operator: ~A." f))))
  
  (defun lookup (symbol &optional (env *global-env*))
    (if env
  
negative.code:                                     (loop for sexp in body
                                            for last-value = (clutter-eval sexp env)
                                            finally (return last-value)))))))))
            (cons 'wrap
                  (make-function
                   (make-clutter-operator
                    :function (lambda (*denv* values)
                                (make-function (car values))))))
            (cons 'unwrap
                  (make-function
                   (make-clutter-operator
                    :function (lambda (*denv* values)
                                (clutter-function-operator (car values))))))
            (cons 'def!
                  (make-clutter-operator
                   :function (lambda (*denv* values)
                               (destructuring-bind (var value)
                                   values
                                 (extend *denv* var (clutter-eval value *denv*))
                                 var))))
            (cons 'set!
                  (make-clutter-operator
  