Datalog blog

datalog-jointest.clj

(defn join-test3 [xs ys]
  (let [db-base (make-database
                 (relation :last-first-email [:last :first :email])
                 (index :last-first-email :email)
                 (relation :email-height [:email :height])
                 (index :email-height :email))
        rules (rules-set
               (<- (:first-height :first ?f :height ?h)
                   (:last-first-email :last ?l :first ?f :email ?e)
                   (:email-height :email ?e :height ?h)))
        workplan (build-work-plan
                  rules
                  (?- :first-height :first ?f :height ?h))
        db (time (->> xs
                      (map (fn [[l f e]]
                             [:last-first-email :last l :first f :email e]))
                      (apply add-tuples db-base)))
        db (time  (->> ys
                       (map (fn [[e h]] [:email-height :email e :height h]))
                       (apply add-tuples db)))]
    (run-work-plan workplan db {})))

query-datalog.clj

(def db-base (make-database
                 (relation :last-first-email [:last :first :email])
                 (relation :email-height [:email :height])))

(def db
  (add-tuples db-base
              [:last-first-email :last "Doe" :first "John" :email "[email protected]"]
              [:last-first-email :last "Doe" :first "Jane" :email "[email protected]"]
              [:email-height :email "[email protected]" :height 73]
              [:email-height :email "[email protected]" :height 71]))

(def rules (rules-set
            (<- (:first-height :first ?f :height ?h)
                (:last-first-email :last ?l :first ?f :email ?e)
                (:email-height :email ?e :height ?h))))

(def wp (build-work-plan
         rules
         (?- :first-height :first ?f :height ?h)))

(run-work-plan wp db {})
;; ({:height 73, :first "Jane"} {:height 71, :first "John"})

query-datomic.clj

(q '[:find ?first ?height
     :in $a $b
     :where [$a ?last ?first ?email] [$b ?email ?height]]
   [["Doe" "John" "[email protected]"]
    ["Doe" "Jane" "[email protected]"]]
   [["[email protected]" 73]
    ["[email protected]" 71]])
;; #<HashSet [["Jane" 73], ["John" 71]]>