Add solutions to section 08-conditionals and 09-higher-order-functions

08_conditionals.clj

@@ -1,37 +1,44 @@
+(defn explain-exercise-velocity [exercise-term]
+  (case exercise-term
+        :ten-mph      :pretty-fast
+        :watching-tv  :not-so-fast))
+
+
 
   ; "You will face many decisions"
-  (= __ (if (false? (= 4 5))
+  (= :a (if (false? (= 4 5))
           :a
           :b))
 
   ; "Some of them leave you no alternative"
-  (= __ (if (> 4 3)
+  (= [] (if (> 4 3) ;; J - This is the equivalent of an if statement without an else.
-          []))
+          []))      ;; returns nil if false as seen below.
 
   ; "And in such a situation you may have nothing"
-  (= __ (if (nil? 0)
+  (= nil (if (nil? 0)
           [:a :b :c]))
 
   ; "In others your alternative may be interesting"
   (= :glory (if (not (empty? ()))
               :doom
-              __))
+              :glory))
 
   ; "You may have a multitude of possible paths"
   (let [x 5]
-    (= :your-road (cond (= x __) :road-not-taken
+    (= :your-road (cond (= x 3) :road-not-taken
-                        (= x __) :another-road-not-taken
+                        (= x 2) :another-road-not-taken
-                        :else __)))
+                        :else :your-road)))  ;; J - The syntax and formatting of this statement
+                                             ;; are crucial in writing these statements correctly.
 
   ; "Or your fate may be sealed"
-  (= 'doom (if-not (zero? __)
+  (= 'doom (if-not (zero? 1)
           'doom
           'more-doom))
 
   ; "In case of emergency, go fast"
-  (= "pretty fast"
+  (= :pretty-fast
-     (explain-exercise-velocity __))
+     (explain-exercise-velocity :ten-mph))
 
   ; "But admit it when you don't know what to do"
-  (= __
+  (= :not-so-fast
      (explain-exercise-velocity :watching-tv))

09_higher_order_functions.clj

@@ -1,32 +1,33 @@
 
   ; "The map function relates a sequence to another"
-  (= [__ __ __] (map (fn [x] (* 4 x)) [1 2 3]))
+  (= [4 8 12] (map (fn [x] (* 4 x)) [1 2 3]))
 
   ; "You may create that mapping"
-  (= [1 4 9 16 25] (map (fn [x] __) [1 2 3 4 5]))
+  (= [1 4 9 16 25] (map (fn [x] (* x x)) [1 2 3 4 5]))
 
   ; "Or use the names of existing functions"
-  (= __ (map nil? [:a :b nil :c :d]))
+  (= '(false false true false false) (map nil? [:a :b nil :c :d]))
 
   ; "A filter can be strong"
-  (= __ (filter (fn [x] false) '(:anything :goes :here)))
+  (= () (filter (fn [x] false) '(:anything :goes :here)))
 
   ; "Or very weak"
-  (= __ (filter (fn [x] true) '(:anything :goes :here)))
+  (= '(:anything :goes :here) (filter (fn [x] true) '(:anything :goes :here)))
 
   ; "Or somewhere in between"
-  (= [10 20 30] (filter (fn [x] __) [10 20 30 40 50 60 70 80]))
+  (= [10 20 30] (filter (fn [x] (<= x 30)) [10 20 30 40 50 60 70 80]))
 
   ; "Maps and filters may be combined"
-  (= [10 20 30] (map (fn [x] __) (filter (fn [x] __) [1 2 3 4 5 6 7 8])))
+  (= [10 20 30] (map (fn [x] (* x 10))
+                       (filter (fn [x] (<= x 3)) [1 2 3 4 5 6 7 8])))
 
   ; "Reducing can increase the result"
-  (= __ (reduce (fn [a b] (* a b)) [1 2 3 4]))
+  (= 24 (reduce (fn [a b] (* a b)) [1 2 3 4]))
 
   ; "You can start somewhere else"
-  (= 2400 (reduce (fn [a b] (* a b)) __ [1 2 3 4]))
+  (= 2400 (reduce (fn [a b] (* a b)) (cons 100 [1 2 3 4])))
 
   ; "Numbers are not the only things one can reduce"
   (= "longest" (reduce (fn [a b]
-                         (if (< __ __) b a))
+                         (if (< (count a)) b a))
                        ["which" "word" "is" "longest"]))