Add atoms.

src/koans/atoms.clj

@@ -0,0 +1,31 @@
+(def atomic-clock (atom 0))
+
+(meditations
+  "Atoms are like refs"
+  (= __ @atomic-clock)
+
+  "You can change at the swap meet"
+  (= __ (do
+          (swap! atomic-clock inc)
+          @atomic-clock))
+
+  "Keep taxes out of this: swapping requires no transaction"
+  (= 5 (do
+         __
+         @atomic-clock))
+
+  "Any number of arguments might happen during a swap"
+  (= __ (do
+          (swap! atomic-clock + 1 2 3 4 5)
+          @atomic-clock))
+
+  "Atomic atoms are atomic"
+  (= __ (do
+          (compare-and-set! atomic-clock 100 :fin)
+          @atomic-clock))
+
+  "When your expectations are aligned with reality things, proceed that way"
+  (= :fin (do
+            (compare-and-set! __ __ __)
+            @atomic-clock))
+  )