New Example in PrologMUD

% Looking causes Percepts
oper(Agent, look(Agent)),
     [ h(in, Agent, Here),
       believe(Agent, h(_, Here, _)),
       Here \= Agent
       ], % path(Here, There)
     [ precept(Agent, h(_, Here, _)) ]).

% Return an operator after substituting Agent for Agent.
oper(Agent, goto_dir(Agent, walk, ExitName),
     [ h(in, Agent, Here),
       believe(Agent, h(exit(ExitName), Here, _)),
       h(exit(ExitName), Here, There),
       h(exit(ReverseExit), There, Here)),
       Here \= Agent, There \= Agent, Here \= There, ReverseExit \= ExitName
       ], % path(Here, There)
     [ ~h(in, Agent, Here),
        precept_local(Here, leaves(Agent, Here, ExitName)),
        h(in, Agent, There),
        precept_local(There,arrives(Agent, There, ReverseExit)),
     ]).

% the World agent has a *goal that no events go unhandled
oper(world, handle_events(Here),
     [ precept_local(Here, Event)]
     [ ~precept_local(Here, Event),
       for((h(in, Agent, Here),prop(Agent,inherited(preceptQ))),precept(Agent,Event))]).

% deducer Agents who preceive leavers from some exit believe the leaving point is an exit
oper(Agent, precept(Agent, leaves(Someone, Here, ExitName)),
     [ did(goto_dir(Someone, walk, ExitName)),
       prop(Agent,inherited(deducer)),
       h(in, Agent, Here) ],
     [ believe(Agent, h(exit(ExitName), Here, _)),
       believe(Agent, prop(Someone,inherited(actor)))]).

% deducer Agents who preceive arivers from some entrance believe the entry location is an exit
oper(Agent, precept(Agent, arrives(Someone, Here, ExitName)),
     [ did(goto_dir(Someone, walk, ExitName)),
       prop(Agent,inherited(deducer)),
       h(in, Agent, Here) ],
     [ believe(Agent, h(exit(ExitName), Here, _)),
       believe(Agent, prop(Someone,inherited(actor)))]).