---

       # MUD another simple little text-adventure space
       # let us try to make a slightly more interesting world
[hear] (define make-table
         (lambda (lst)
           (crunch (? x / ? h /
                  assign name (car / x) /
                  assign obj (cdr / x) /
                  hash-add (h) (name) (obj))
               (append (hash-null) (lst)))));

       # note, the quoted strings below are just represented as a big number,
       # nothing special
[hear] (define geo-map
         (make-table
          (map
           (? name (cons (name) (room new (name))))
           (vector "boston" "dublin" "paris" "genoa"))));

[hear] (define my-links
         (map
          (? entry (assign src (car / entry) /
                   assign dest (cdr / entry) /
                   door new (geo-map / src) (geo-map / dest)))
          (vector
           (cons "boston" "dublin")
           (cons "dublin" "paris")
           (cons "boston" "paris")
           (cons "paris" "genoa"))));

[hear] (define myrobo (robo new));

[hear] (myrobo set-room (geo-map "dublin"));

[hear] (demo / myrobo get-room name);
   This expression is embedded in the message in the form (equal expression value)
   where value is "dublin"
   (quoted strings are guessed; they are represented in the message as ordinary numbers)

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "boston"

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "paris"

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "dublin"

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "boston"

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "paris"

[hear] (myrobo update);

[hear] (demo / myrobo get-room name);
   evaluates to: "genoa"

       # all characters should update together
[hear] (class world (the-places the-links)
              (field things (container new))
              (field names (cell new (hash-null)))
              (field places (cell new 0))
              (field links (cell new 0))
              (method new
                  (begin
                (places set
                   (make-table
                    (map
                     (? name (cons (name) (room new (name))))
                     (the-places))))
                (links set
                   (map
                    (? entry (assign src (car / entry) /
                             assign dest (cdr / entry) /
                             door new
                             (places get / src)
                             (places get / dest)))
                    (the-links)))))
              (method add (lambda (place name val)
                    (begin
                      (val set-room (places get / place))
                      (val set-name / name)
                      (names set (hash-add (names get)
                               (name)
                               (val)))
                      (things add (val)))))
              (method find (lambda (n) (names get (n) get-room name)))
              (method reachable (lambda (place)
                      (let ((exits
                         (select-match (lambda (x)
                                 (instanceof door (x)))
                               (places get (place) inventory))))
                        (map (? door (door access-from
                               (places get / place)
                               name))
                         (exits)))))
              (method update (begin
                   (map (? x (x update))
                        (things inventory))
                   (true))));

[hear] (define geo-world
         (world new
            (vector "boston" "dublin" "paris" "genoa")
            (vector
             (cons "boston" "dublin")
             (cons "dublin" "paris")
             (cons "boston" "paris")
             (cons "paris" "genoa"))));

[hear] (geo-world add "dublin" "robo1" (robo new));

[hear] (geo-world add "genoa" "robo2" (robo new));

[hear] (demo / geo-world find "robo1");
   evaluates to: "dublin"

[hear] (demo / geo-world find "robo2");
   evaluates to: "genoa"

[hear] (geo-world update);

[hear] (demo / geo-world find "robo1");
   evaluates to: "boston"

[hear] (demo / geo-world find "robo2");
   evaluates to: "paris"

[hear] (demo / geo-world reachable "boston");
   evaluates to: (vector "dublin" "paris")

[hear] (demo / geo-world reachable "genoa");
   evaluates to: (vector "paris")