March 2014 update

Task/Zebra-puzzle/Clojure/zebra-puzzle.clj

@@ -0,0 +1,42 @@
+(ns zebra.core
+  (:refer-clojure :exclude [==])
+  (:use [clojure.core.logic]
+        [clojure.tools.macro :as macro]))
+
+(defne lefto [x y l]
+       ([_ _ [x y . ?r]])
+       ([_ _ [_ . ?r]] (lefto x y ?r)))
+
+(defn nexto [x y l]
+  (conde
+    ((lefto x y l))
+    ((lefto y x l))))
+
+(defn zebrao [hs]
+  (macro/symbol-macrolet [_ (lvar)]
+    (all
+      (== [_ _ _ _ _] hs)
+      (membero ['englishman _ _ _ 'red] hs)
+      (membero ['swede _ _ 'dog _] hs)
+      (membero ['dane _ 'tea _ _] hs)
+      (lefto [_ _ _ _ 'green] [_ _ _ _ 'white] hs)
+      (membero [_ _ 'coffee _ 'green] hs)
+      (membero [_ 'pallmall _ 'birds _] hs)
+      (membero [_ 'dunhill _ _ 'yellow] hs)
+      (== [_ _ [_ _ 'milk _ _] _ _ ] hs)
+      (firsto hs ['norwegian _ _ _ _])
+      (nexto [_ 'blend _ _ _] [_ _ _ 'cats _ ] hs)
+      (nexto [_ _ _ 'horse _] [_ 'dunhill _ _ _] hs)
+      (membero [_ 'bluemaster 'beer _ _] hs)
+      (membero ['german 'prince _ _ _] hs)
+      (nexto ['norwegian _ _ _ _] [_ _ _ _ 'blue] hs)
+      (nexto [_ _ 'water _ _] [_ 'blend _ _ _] hs)
+      (membero [_ _ _ 'zebra _] hs))))
+
+(let [solns (run* [q] (zebrao q))
+      soln (first solns)
+      zebra-owner (->> soln (filter #(= 'zebra (% 3))) first (#(% 0)))]
+  (println "solution count:" (count solns))
+  (println "zebra owner is the" zebra-owner)
+  (println "full solution (in house order):")
+  (doseq [h soln] (println " " h)))