anchor.diff: -;;;;; Copyright (c) 2012,2014 Sven Michael Klose <pixel@copei.de>
  +; Copyright (c) 2012,2014–2015 Sven Michael Klose <pixel@copei.de>
   
   (defun cart-current ()      (!?   (session 'cart)      (phphash-alist !)))
   (defun cart-undos ()        (!?   (session 'cart-undo) (array-list !)))
  
positive.code:   (not (zero? (length (cart-current)))))
  
  (defmacro filter-cart (&rest body)
    `(= (cart-current) (filter [,@body] (cart-current))))
  
  (defun cart-redirect ()
    (action-redirect :update 'cart))
  
negative.code: (defun cart-update ()
    (when (has-form?)
      (cart-add-undo)
      (@ #'cart-update-item (form-alists))
      (action-redirect)))
  
  (defun cart (x)
  