Harnessing the Power of Flow Control

src/wonderland/chapter_2.clj

@@ -73,3 +73,88 @@
 (some #{nil} [nil nil nil])
 (some #{false} [false false false])
 (some #{true} [true true true])
+
+; Harnessing the Power of Flow Control
+(if true "it is true" "it is false")
+(if false "it is true" "it is false")
+(if nil "it is true" "it is false")
+(if (= :drinkme :drinkme)
+  "Try it"
+  "Don't try it")
+
+(let [need-to-grow-small (> 5 3)]
+  (if need-to-grow-small
+    "drink bottle"
+    "don't drink bottle"))
+
+(if-let [need-to-grow-small (> 5 1)]
+  "drink bottle"
+  "don't drink bottle")
+
+(defn drink [need-to-grow-small]
+  (when need-to-grow-small "drink bottle"))
+
+(drink true)
+(drink false)
+
+(when-let [need-to-grow-small true]
+  "drink bottle")
+(when-let [need-to-grow-small false]
+  "drink bottle")
+
+(let [bottle "drinkme"]
+  (cond
+    (= bottle "poison") "don't touch"
+    (= bottle "drinkme") "grow smaller"
+    (= bottle "empty") "all gone"))
+
+(let [x 5]
+  (cond
+    (> x 10) "bigger than 10"
+    (> x 4)  "bigger than 4"
+    (> x 3)  "bigger than 3"))
+
+(let [x 5]
+  (cond
+    (> x 3)  "bigger than 3"
+    (> x 10) "bigger than 10"
+    (> x 4)  "bigger than 4"))
+
+(let [x 1]
+  (cond
+    (> x 10) "bigger than 10"
+    (> x 4)  "bigger than 4"
+    (> x 3)  "bigger than 3"))
+
+(let [bottle "mystery"]
+  (cond
+    (= bottle "poison") "don't touch"
+    (= bottle "drinkme") "grow smaller"
+    (= bottle "empty") "all gone"
+    :else "unknown"))
+
+(let [bottle "mystery"]
+  (cond
+    (= bottle "poison") "don't touch"
+    (= bottle "drinkme") "grow smaller"
+    (= bottle "empty") "all gone"
+    "default" "unknown"))
+
+(let [bottle "drinkme"]
+  (case bottle
+    "poison" "don't touch"
+    "drinkme" "grow smaller"
+    "empty" "all gone"))
+
+(let [bottle "mystery"]
+  (case bottle
+    "poison" "don't touch"
+    "drinkme" "grow smaller"
+    "empty" "all gone"))
+
+(let [bottle "mystery"]
+  (case bottle
+    "poison" "don't touch"
+    "drinkme" "grow smaller"
+    "empty" "all gone"
+    "unknown"))