Merge 7fecd24dd6 into 2eb2dfe36a

ideaboard.txt

@@ -1,7 +1,6 @@
 Concepts / Language Features
 =====
 new record syntax
-Agents
 Vars
 state identity lifetime
 Metadata

resources/koans.clj

@@ -203,4 +203,9 @@
                         5
                         :hello
                         (6 :this :are)
-                        ]}]]
+                        ]}]
+ ["21_agents" {"__" [true
+                     10
+                     10
+                     12
+                     12]}]]

src/koans/21_agents.clj

@@ -0,0 +1,32 @@
+(meditations
+ (let [agent-example (agent 10)]
+
+   "Creating an Agent is as simple as assigning a value to it"
+   (= __ (instance? clojure.lang.Agent agent-example))
+
+   "To get agent's value you dereference it"
+   (= __ @agent-example)
+
+   "To change agent's value you can use 'send' function. Send takes as parameters, agent, action and arguments,
+    it returns immediately but the action is prccessed in a separate thread and it's the result, of action,
+    that gets assigned to agent's state"
+   (= __ (do
+           (send agent-example + 2)
+           @agent-example))
+
+   "You can't just send a value to agent it needs to be a function"
+   (= __ (do
+           (set-error-mode! agent-example :continue)
+           (send agent-example 20)
+           @agent-example))
+
+   "You can create validations for states that agent is allowed to take"
+   (= __ (do
+           (set-validator! agent-example #(even? %))
+           (try
+             (send agent-example + 1)
+             (catch IllegalStateException e))
+           @agent-example))
+
+   "It's a good idea to clean up any not finished agents after you are done"
+   (shutdown-agents)))