gistfile1.clj

(use 'clojure.contrib.datalog)
(use 'clojure.contrib.datalog.rules)
(use 'clojure.contrib.datalog.database)
(use 'clojure.contrib.datalog.util)

(def d (make-database
		(relation :person [:name :room-id :seat-number])
		(index :person :name)))

(def db (add-tuples d
           [:person :name "Albert" :room-id 1 :seat-number 1]
           [:person :name "Tom" :room-id 1 :seat-number 2]
           [:person :name "Ted" :room-id 1 :seat-number 3]
           [:person :name "Tom" :room-id 2 :seat-number 3]))

(def rules
	 (rules-set 
	  (<- (:rooms-used :room ?x) (:person :name ?notused :room-id ?x :seat-number ?notusedeither))
	  (<- (:room-use :room ?x :person ?p :seat ?s) (:person :name ?p :room-id ?x :seat-number ?s))))

(def rooms-wp (build-work-plan rules (?- :rooms-used :room ?x)))
(run-work-plan rooms-wp db {})

(defn who-is-in-room
  [room-id]
  (let [in-room (build-work-plan rules (?- :room-use :room '??roomid :person ?p :seat ?s))]
	(into [] (map #(% :person) (run-work-plan in-room db {'??roomid room-id})))))

(defn seat-in-room
  [room-id]
  (let [in-room (build-work-plan rules (?- :room-use :room '??roomid :person ?p :seat ?s))]
	(into [] (map #(% :seat) (run-work-plan in-room db {'??roomid room-id})))))

(defn who-is-in-all-rooms
  []
  (let [allrooms (run-work-plan rooms-wp db {})]
	(into [] (map (fn [rmid] {:room-id (:room rmid) :seat-number (seat-in-room (:room rmid)) :players (who-is-in-room (:room rmid))}) allrooms))))

(who-is-in-all-rooms)