integero

integero.clj

(defn integero**
  [n x]
  (conde ((== n x))
         ((== (- n) x))
         ((integero** (inc n) x))))

(defmacro integero*
  [x]
  `(fn [a#]
     (let [w# (walk a# ~x)]
       (if-not (lvar? w#)
         (if (integer? w#)
           a#
           nil)
         (-inc
          (mplus*
           (bind* a# (== 0 ~x))
           (bind* a# (integero** 1 ~x))))))))

(defn integero
  [x]
  (integero* x))

(do
  (assert (empty? (run 4 [q] (integero 8.4))))
  (assert (= ['_.0]) (run 4 [q] (integero 8)))
  (assert (= 4 (count (run 4 [q] (integero q))))))