runtime_polymorphism and lazy_sequences done

src/koans/09_higher_order_functions.clj

@@ -3,33 +3,33 @@
 
 (meditations
   "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 31)) [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 4)) [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)) 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) (count b)) b a))
                        ["which" "word" "is" "longest"])))

src/koans/10_runtime_polymorphism.clj

@@ -10,19 +10,19 @@
                    "!")))
 
 (defmulti diet (fn [x] (:eater x)))
-(defmethod diet :herbivore [a] __)
-(defmethod diet :carnivore [a] __)
-(defmethod diet :default [a] __)
+(defmethod diet :herbivore [a] (str (a :name) " eats veggies."))
+(defmethod diet :carnivore [a] (str (a :name) " eats animals."))
+(defmethod diet :default [a] (str "I don't know what " (a :name) " eats."))
 
 (meditations
   "Some functions can be used in different ways - with no arguments"
-  (= __ (hello))
+  (= "Hello World!" (hello))
 
   "With one argument"
-  (= __ (hello "world"))
+  (= "Hello, you silly world." (hello "world"))
 
   "Or with many arguments"
-  (= __
+  (= "Hello to this group: Peter, Paul, Mary!"
      (hello "Peter" "Paul" "Mary"))
 
   "Multimethods allow more complex dispatching"

src/koans/11_lazy_sequences.clj

@@ -3,26 +3,26 @@
 
 (meditations
   "There are many ways to generate a sequence"
-  (= __ (range 1 5))
+  (= '(1 2 3 4) (range 1 5))
 
   "The range starts at the beginning by default"
-  (= __ (range 5))
+  (= [0 1 2 3 4] (range 5))
 
   "Only take what you need when the sequence is large"
   (= [0 1 2 3 4 5 6 7 8 9]
-     (take __ (range 100)))
+     (take 10 (range 100)))
 
   "Or limit results by dropping what you don't need"
   (= [95 96 97 98 99]
-     (drop __ (range 100)))
+     (drop 95 (range 100)))
 
   "Iteration provides an infinite lazy sequence"
-  (= __ (take 8 (iterate (fn [x] (* x 2)) 1)))
+  (= [1 2 4 8 16 32 64 128] (take 8 (iterate (fn [x] (* x 2)) 1)))
 
   "Repetition is key"
   (= [:a :a :a :a :a :a :a :a :a :a]
-     (repeat 10 __))
+     (repeat 10 :a))
 
   "Iteration can be used for repetition"
   (= (repeat 100 "hello")
-     (take 100 (iterate ___ "hello"))))
+     (take 100 (iterate (fn [x] x) "hello"))))