gistfile1.txt

(ns temp
  (:refer-clojure :exclude [==])
  (:use [clojure.core.logic])
  (:use [clojure.core.logic.pldb]))

(db-rel parent x y)
(db-rel male x)
(db-rel female x)

(defn child [x y]
  (parent y x))

(defn son [x y]
  (all
    (child x y)
    (male x)))

(def g 
  (db 
    [parent 'Dad 'Junior]
    [male 'Dad]
    [male 'Junior]))

(with-db g (run* [q] (son 'Junior q)))
;;=> (Dad)

(defn son2 [x y]
  (child x y)
  (male x))

(with-db g (run* [q] (son2 'Junior q)))
;;=> (_0) ;;wut? We've got two variables, we've tested them both, where's the fresh coming from and why isn't it binding?

(defn son3 [x y]
  (fresh [z]
         (child x y)
         (male x)))

(with-db g (run* [q] (son3 'Junior q)))
;;=> (Dad) ;;wut? Where did we bind z with anything? What has z to do with the answer? Why can't we take it out, like son2?