core.logic básico

(ns clj-sp.core
  (:require [clojure.core.logic.pldb :as pldb]
            [clojure.core.logic :refer :all])
  (:refer-clojure :exclude [==]))

(pldb/db-rel parent p1 p2)

;               :jose
;:joao  :mario  :josefa
;:joana :maria  :carlos
;               :carla


(def facts
  (pldb/db
    [parent :maria :joao]
    [parent :mario :joao]
    [parent :maria :joana]
    [parent :mario :joana]
    [parent :carlos :maria]
    [parent :carla :maria]
    [parent :jose :mario]
    [parent :josefa :mario]))

(defn grandparent
  [x y]
  (fresh [z]
         (parent x z)
         (parent z y)))

(pldb/with-db facts
  (run* [q]
        (grandparent :jose q)))
; => (:joao :joana)

(pldb/with-db facts
  (run* [q]
        (fresh [gparent gchild]
               (grandparent gparent gchild)
               (== q [gparent gchild]))))
; => ([:carla :joana] [:carla :joao] [:jose :joao] [:jose :joana] [:carlos :joana] [:carlos :joao] [:josefa :joao] [:josefa :joana])

(defn ancestor
  [x y]
  (fresh [z]
         (conde [(parent x z)
                 (ancestor z y)]
                [(parent x y)])))

(pldb/with-db facts
              (run* [q]
                    (fresh [anc p]
                           (ancestor anc p)
                           (== q [anc p]))))
; => ([:mario :joao] [:carla :maria] [:maria :joana] [:maria :joao] [:mario :joana] [:jose :mario] [:carlos :maria] [:josefa :mario] [:carla :joana] [:carla :joao] [:jose :joao] [:jose :joana] [:carlos :joana] [:carlos :joao] [:josefa :joao] [:josefa :joana])