Add datatypes.

src/koans/datatypes.clj

@@ -0,0 +1,45 @@
+(defrecord Nobel [prize])
+(deftype Pulitzer [prize])
+
+(defprotocol Award
+  (present [this recipient]))
+
+(defrecord Oscar [category]
+  Award
+  (present [this recipient]
+    (print (str "Congratulations on your "
+                (:category this) " Oscar, "
+                recipient
+                "!"))))
+
+(deftype Razzie [category]
+  Award
+  (present [this recipient]
+    __))
+
+(meditations
+  "Holding records is meaningful only when the record is worthy of you"
+  (= __ (.prize (Nobel. "peace")))
+
+  "Types are quite similar"
+  (= __ (.prize (Pulitzer. "literature")))
+
+  "Records may be treated like maps"
+  (= __ (:prize (Nobel. "physics")))
+
+  "While types may not"
+  (= __ (:prize (Pulitzer. "poetry")))
+
+  "Further study reveals why"
+  (= __
+     (map map? [(Nobel. "chemistry")
+                (Pulitzer. "music")]))
+
+  "Either sort of datatype can define methods in a protocol"
+  (= __
+     (with-out-str (present (Oscar. "Best Picture") "Evil Alien Conquerors")))
+
+  "Surely we can implement our own by now"
+  (= "You're really the Worst Picture, Final Destination 5... sorry."
+     (with-out-str (present (Razzie. "Worst Picture") "Final Destination 5"))))
+