pldb_ex.clj

(ns pldb-ex.core
  (:refer-clojure :exclude [==])
  (:require [clojure.core.logic :as l
             :refer [run run* fresh == membero nafc]]
            [clojure.core.logic.pldb :as pldb]))

;sku(wun_1).  sku(wun_2).  sku(wun_3).
;
;booking(wun_1, monday).
;booking(wun_2, monday).
;booking(wun_1, tuesday).
;booking(wun_3, tuesday).
;booking(wun_2, thursday).
;booking(wun_1, friday).
;booking(wun_3, friday).
;booking(wun_2, saturday).
;booking(wun_3, saturday).
;
;available(Sku, Date) :-
;sku(Sku),
;Dates = [monday,tuesday,wednesday,thursday,friday,saturday],
;member(Date, Dates),
;not(booking(Sku, Date)).

(pldb/db-rel sku)
(pldb/db-rel booking)

(def facts
  (pldb/db
    [sku :wun1]
    [sku :wun2]
    [sku :wun3]
    [booking :wun1 :monday]
    [booking :wun2 :monday]
    [booking :wun1 :tuesday]
    [booking :wun3 :tuesday]
    [booking :wun2 :thursday]
    [booking :wun1 :friday]
    [booking :wun3 :friday]
    [booking :wun2 :saturday]
    [booking :wun3 :saturday]))

(defn availableo []
  (pldb/with-db facts
    (run* [Sku date]
      (sku Sku)
      (membero date [:monday :tuesday :wednesday :thursday :friday])
      (nafc booking Sku date))))

;; (availableo) =>
;; ([:wun2 :tuesday] [:wun3 :monday] [:wun2 :wednesday] [:wun2 :friday]
;;  [:wun3 :wednesday] [:wun1 :wednesday] [:wun3 :thursday] [:wun1 :thursday])