From c1e56f5c29a07469cd0448a4cfa03d09a939acf1 Mon Sep 17 00:00:00 2001
From: Oli Clive-Griffin <o.clivegriffin@gmail.com>
Date: Thu, 3 Jun 2021 23:17:08 +1200
Subject: [PATCH] finished up to 14_recursion

---
 src/koans/13_creating_functions.clj | 16 ++++++++--------
 src/koans/14_recursion.clj          | 20 ++++++++++++++------
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/src/koans/13_creating_functions.clj b/src/koans/13_creating_functions.clj
index 7d84bc8..35910bd 100644
--- a/src/koans/13_creating_functions.clj
+++ b/src/koans/13_creating_functions.clj
@@ -5,31 +5,31 @@
 
 (meditations
   "One may know what they seek by knowing what they do not seek"
-  (= [__ __ __] (let [not-a-symbol? (complement symbol?)]
+  (= [true false true] (let [not-a-symbol? (complement symbol?)]
                   (map not-a-symbol? [:a 'b "c"])))
 
   "Praise and 'complement' may help you separate the wheat from the chaff"
   (= [:wheat "wheat" 'wheat]
-       (let [not-nil? ___]
+       (let [not-nil? (complement nil?)]
          (filter not-nil? [nil :wheat nil "wheat" nil 'wheat nil])))
 
   "Partial functions allow procrastination"
   (= 20 (let [multiply-by-5 (partial * 5)]
-          (___ __)))
+          (multiply-by-5 4)))
 
   "Don't forget: first things first"
-  (= [__ __ __ __]
+  (= [:a :b :c :d]
        (let [ab-adder (partial concat [:a :b])]
-         (ab-adder [__ __])))
+         (ab-adder [:c :d])))
 
   "Functions can join forces as one 'composed' function"
   (= 25 (let [inc-and-square (comp square inc)]
-          (inc-and-square __)))
+          (inc-and-square 4)))
 
   "Have a go on a double dec-er"
-  (= __ (let [double-dec (comp dec dec)]
+  (= 8 (let [double-dec (comp dec dec)]
           (double-dec 10)))
 
   "Be careful about the order in which you mix your functions"
-  (= 99 (let [square-and-dec ___]
+  (= 99 (let [square-and-dec (comp dec square)]
           (square-and-dec 10))))
diff --git a/src/koans/14_recursion.clj b/src/koans/14_recursion.clj
index ca29784..4c9d60f 100644
--- a/src/koans/14_recursion.clj
+++ b/src/koans/14_recursion.clj
@@ -3,21 +3,29 @@
 
 (defn is-even? [n]
   (if (= n 0)
-    __
-    (___ (is-even? (dec n)))))
+    true
+    (not (is-even? (dec n)))))
 
 (defn is-even-bigint? [n]
   (loop [n   n
          acc true]
     (if (= n 0)
-      __
+      acc
       (recur (dec n) (not acc)))))
 
 (defn recursive-reverse [coll]
-  __)
-
+  (loop [coll coll
+         acc  '()]
+    (if (empty? coll)
+      acc
+      (recur (rest coll) (conj acc (first coll)))))) 
+    
 (defn factorial [n]
-  __)
+   (loop [n   n
+          acc  1]
+    (if (= n 1)
+      acc
+      (recur (dec n) (* acc  n)))))
 
 (meditations
   "Recursion ends with a base case"