Using core.logic to query custom data sources.

gistfile1.clj

(ns extend-core-logic.core
    (:require [clojure.core.logic :refer :all]
              [clojure.core.logic.protocols :refer [walk]]
              [clojure.java.io :as jio]
              [clojure.string :as string])
    (:import [java.io BufferedReader StringReader]))

;; from: http://federalgovernmentzipcodes.us/
(defn load-db []
  (let [data (java.io.BufferedReader. (java.io.StringReader. (slurp "/Users/tim/Downloads/free-zipcode-database.csv")))
        data (->> (line-seq data)
             (drop 1)
             (map #(clojure.string/split % #","))
             (map (fn [[idx zip _ nm]]
                    [(read-string zip)
                     (read-string nm)])))]
    {:zip->city
     (reduce
      (fn [acc [k v]]
        (assoc acc k v))
      {}
      data)
     :city->zip
     (reduce
      (fn [acc [v k]]
        (update-in acc [k] (fnil conj #{}) v))
      {}
      data)}))

(def ^:dynamic *db* (load-db))

(-> *db* :city->zip (get "DALLAS"))


(-> *db* :zip->city (get "75356"))

(defn debug [x]
  (println x)
  x)

(defn zipcodeo [zip city]
  (fn [a]
    (let [zip (walk a zip)
          city (walk a city)]
      (condp = [(not (lvar? zip))
                (not (lvar? city))]
        [true false] (unify a city (-> *db* :zip->city (get zip)))

        
        [false true] (->> (-> *db* :city->zip (get city))
                          (map #(unify a zip %))
                          to-stream)
        [true true]  (when (= city (-> *db* :zip->city (get zip)))
                       a)))))

(run* [q]
      (zipcodeo "75356" q))

(run* [q]
      (zipcodeo q "DALLAS"))

(run* [q]
      (fresh [x]
             (membero x ["DALLAS" "DENVER"])
             (== q "75356")            
             (zipcodeo q x)))

(run* [q]
      (fresh [x]
             (membero x ["DALLAS"])
             (== q "75356")
             (zipcodeo q x)))

(run* [q]
      (fresh [x]
             (membero x ["DENVER"])
             (== q "75356")
             (zipcodeo q x)))