Implemented a version of the text game in chapter 5.

Implemented a version of the Wizard's Adventure text game from chapter
5. This implementation doesn't use quasiquoting to store the data.
Instead maps and strings are used.

src/land_of_lisp/ch5_the_wizards_adventure.clj

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+(ns land-of-lisp.ch5_the_wizards_adventure
+  "In this game, you are a wizard’s apprentice. You’ll explore the wizard’s house.")
+
+
+;; Locations
+(defn describe-location
+  "Describes the location you are in."
+  [location nodes] (get nodes location))
+
+
+;; Paths
+(defn- describe-path
+  "Describes a path from the location you are in."
+  [path]
+  (str "There is a " (nth path 2) " going " (second path) " from here."))
+
+(defn describe-paths
+  "Describes all the paths from the location you are in."
+  [location edges]
+  (let [paths (get edges location)]
+    (map describe-path paths)))
+
+(defn- find-location-from-direction
+  "Finds the location when walking in the given direction."
+  [location direction edges]
+  (let [paths (get edges location)]
+    (ffirst (filter #(= (second %) direction) paths))))
+
+
+;; Objects
+(defn objects-at
+  "Describes what objects are present and visible at your location."
+  [location objs obj-locs]
+  (filter #(= (obj-locs %) location) objs))
+
+(defn- describe-object
+  "Describes an object."
+  [object]
+  (str "You see a " object " on the floor."))
+
+(defn describe-objects-at
+  "Describes all the objects present at location you are in."
+  [location obj obj-locs]
+  (let [objs (objects-at location obj obj-locs)]
+    (map describe-object objs)))
+
+
+;; Adventuring
+(def ^:private location-nodes
+  "A description of each of the locations you can visit."
+  {:living-room "You are in the living-room. A wizard is snoring loudly on the couch."
+   :garden "You are in a beautiful garden. There is a well in front of you."
+   :attic "You are in the attic. There is a giant welding torch in the corner."})
+
+(def ^:private location-edges
+  "The connectivity graph of the locations you can visit."
+  {:living-room [[:garden :west :door]
+                 [:attic :upstairs :ladder]]
+   :garden [[:living-room :east :door]]
+   :attic [[:living-room :downstairs :ladder]]})
+
+(def ^:private objects
+  "The objects that can be found in locations."
+  [:wiskey :bucket :frog :chain])
+
+(def ^:private object-locations
+  "The locations where each object can be found."
+  {:wiskey :living-room
+   :bucket :living-room
+   :frog :garden
+   :chain :garden})
+
+(def ^:private your-adventure
+  "This is your adventure."
+  (ref nil))
+
+(defn start-adventuring
+  "Start or restart your adventure!"
+  ;; Use the default adventure:
+  ([] (start-adventuring location-nodes location-edges objects object-locations))
+
+  ;; Define your own adventure:
+  ([nodes edges objs obj-locs]
+   (dosync (ref-set your-adventure {:location (ffirst edges)
+                                    :nodes nodes
+                                    :edges edges
+                                    :objects objs
+                                    :object-locations obj-locs}))))
+
+(defn look
+  "Look around your location."
+  ([]
+   (when (nil? @your-adventure) (start-adventuring))
+   (apply look (map @your-adventure [:location :nodes :edges :objects :object-locations])))
+
+  ([location nodes edges objs obj-locs]
+   (->> [(describe-location location nodes)
+         (describe-paths location edges)
+         (describe-objects-at location objs obj-locs)]
+     (flatten)
+     (interpose " ")
+     (apply str))))
+
+(defn walk
+  "Walk to a location."
+  ([direction]
+   (let [adventure (map @your-adventure [:location :nodes :edges :objects :object-locations])
+         [new-loc, descr] (apply walk direction adventure)]
+     (when new-loc (dosync (alter your-adventure assoc :location new-loc)))
+     descr))
+
+  ([direction location nodes edges objs obj-locs]
+   (if-let [new-location (find-location-from-direction location direction edges)]
+     [new-location (look new-location nodes edges objs obj-locs)]
+     [nil "You can not walk in that direction."])))
+
+(defn pickup
+  "Pick up an object."
+  ([object]
+   (dosync
+     (let [adventure (map @your-adventure [:location :object-locations])
+           [new-obj-loc, descr] (apply pickup object adventure)]
+       (alter your-adventure assoc :object-locations new-obj-loc)
+       descr)))
+
+  ([object location obj-locs]
+   (if (= (obj-locs object) location)
+     (let [new-obj-locs (assoc obj-locs object :body)]
+       [new-obj-locs (str "You are now carrying " object)])
+     [obj-locs (str "You can not get that here.")])))
+
+(defn inventory
+  "What are you carrying on your adventure?"
+  ([]
+   (let [adventure (map @your-adventure [:objects :object-locations])]
+     (apply inventory adventure)))
+
+  ([objs obj-locs]
+   (objects-at :body objs obj-locs)))
+