queens blog, part 2

nqueenso.clj

(defne nqueenso [l n]
  ([() _])                    ;; queen list empty, s#
  ([[[x y] . t] _]            ;; match/destruct head.tail, ignore n
     (nqueenso t n)
     (membero x (range n))
     (safeo [x y] t)))

queens-run.clj

(defmacro queens-run
  "Search for all N queens solutions"
  [n]
  (let [xnames (->> (range n) (map (fn [_] (gensym "x"))) (into []))
        gen-safeos (fn []
                     (->> (range (dec n))
                          (map (fn [x] [x (range (inc x) n)]))
                          (map (fn [[s ts]]
                                 (map (fn [t] `(safeo [~(nth xnames s) ~s]
                                                      [~(nth xnames t) ~t])) ts)))
                          (apply concat)))
          ]
    `(run* [r#]
           (fresh [~@(map #(nth xnames %) (range n))]
                  ~@(map (fn [x] (list 'membero (xnames x) (into [] (range n)))) (range n))
                  ~@(gen-safeos)
                  (== r# [~@(map (fn [x] [(nth xnames x) x])
                                 (range n))])))))

safeo-loop.clj

(defne safeo
  "Is the queen q safe from all queens in list others"
  [q others]
  ([_ ()])                    ;; others empty, s#
  ([[x1 y1] [[x2 y2] . t]]    ;; destruct q and head.tail of others
     (!= x1 x2)
     (!= y1 y2)
     (project [x1 x2 y1 y2]
       (!= (- x2 x1) (- y2 y1))
       (!= (- x1 y2) (- x2 y1)))
     (safeo [x1 y1] t)))

safeo.clj

(defn safeo [[x1 y1] [x2 y2]]
  (all 
   (!= x1 x2)
   (!= y1 y2)
   (project [x1 x2 y1 y2]
            (!= (- x2 x1) (- y2 y1))
            (!= (- x1 y2) (- x2 y1)))))

Thanks for all the help btw, you're a star. I've gotta bring you a box of chocolates if I manage to get to the next conj :)