The Top-Level Loop

The top-level loop normally reads the query from the user, executes it and prints the answer bindings. In case that a subgoal remains delayed^17.2, the answer bindings alone are not logically correct, they have to be considered in conjunction with the remaining delayed goals. To signal this, the top-level loop first prints the answer bindings and then it checks whether some goals are still delayed. The actions following defers depending on if the graphical tkeclipse or the traditional textual interface is used. With the textual interface, an exception is raised if there are delayed goals; the default handler for this exception prints the goals that are still delayed, so that the user is notified about this situation. This handler can as well print only the number of delayed goals, or ask the user for some action, e.g. force waking of some or all delayed goals. On tkeclipse, the user is informed that there are delayed goals, which can then be examined using the Delayed Goals tool.