zebra.clj

(require '[clojure.core.logic :refer :all])
(require '[clojure.tools.macro :as macro])

(defne righto [x y l]
  ([_ _ [x y . ?r]])
  ([_ _ [_ . ?r]] (righto x y ?r)))

(defn nexto [x y l]
  (conde
    ((righto x y l))
    ((righto y x l))))

(defn zebrao [hs]
  (macro/symbol-macrolet [_ (lvar)]
    (all
     (== [_ _ [_ _ 'milk _ _] _ _] hs)                         
     (firsto hs ['norwegian _ _ _ _])                         
     (nexto ['norwegian _ _ _ _] [_ _ _ _ 'blue] hs)       
     (righto [_ _ _ _ 'ivory] [_ _ _ _ 'green] hs)         
     (membero ['englishman _ _ _ 'red] hs)                    
     (membero [_ 'kools _ _ 'yellow] hs)                      
     (membero ['spaniard _ _ 'dog _] hs)                      
     (membero [_ _ 'coffee _ 'green] hs)                      
     (membero ['ukrainian _ 'tea _ _] hs)                     
     (membero [_ 'lucky-strikes 'oj _ _] hs)                  
     (membero ['japanese 'parliaments _ _ _] hs)              
     (membero [_ 'oldgolds _ 'snails _] hs)                   
     (nexto [_ _ _ 'horse _] [_ 'kools _ _ _] hs)          
     (nexto [_ _ _ 'fox _] [_ 'chesterfields _ _ _] hs))))

(run 1 [q] (zebrao q))