Initial version of Bowling Game Kata

README.md

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+# Solution to the Bowling Game Kata
+
+An initial stab at the [Bowling Game Kata][bsk] in Clojure.
+
+
+[bsk]: http://content.codersdojo.org/code-kata-catalogue/bowling-game/

solution.clj

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+(ns solution
+  (:use clojure.test))
+
+
+(defn split-into-frames
+  "Splits a set of rolls into frames."
+  [rolls]
+  (cond (empty? rolls) []
+        (= (first rolls) 10) (cons '(10 0) (split-into-frames (rest rolls)))
+        :else (cons (take 2 rolls) (split-into-frames (drop 2 rolls)))))
+
+(defn is-strike
+  "true if the first item in rolls is a strike"
+  [rolls]
+  (= 10 (first rolls)))
+
+(defn is-spare
+  "true if the first two items in rolls make a spare"
+  [rolls] 
+  (= 10 (+ (first rolls) (second rolls))))
+
+(defn frame-score
+  "Calculates a frame's score"
+  [rolls]
+  (cond (is-strike rolls) (apply + (take 4 rolls))
+        (is-spare rolls) (apply + (take 3 rolls))
+        :else (apply + (take 2 rolls))))
+
+(defn score 
+  "Scores a collection of rolls"
+  [rolls]
+  (loop [frame-rolls (flatten (split-into-frames rolls))
+         frames 0
+         score 0]
+    (if (or
+          (<= (count frame-rolls) 1)
+          (= frames 10))
+      score
+      (recur (drop 2 frame-rolls) (inc frames) (+ score (frame-score frame-rolls))))))
+
+
+(deftest score-from-example
+  (is (= 133 (score [1 4 4 5 6 4 5 5 10 0 1 7 3 6 4 10 2 8 6])))
+  (is (= 17 (score [0 10 3 1])))
+  (is (= 18 (score [10 3 1])))
+  (is (= 45 (score [10 5 5 6 3])))
+  (is (= 0 (score []))))
+
+
+(run-tests)