Cascalog joins

joins.clj

(def short-urls
  [["http://t.co/yERArQn0"]
   ["http://t.co/gI8TjreI"]
   ["http://t.co/CBsucpNm"]
   ["http://t.co/F74GG1oN"]
   ["http://t.co/hyoXObbU"]])

(def longified-urls
  [["http://t.co/yERArQn0" "http://news.sky.com/story/964624/olympic-lanes-open-traffic-delays-in-london"]
   ["http://t.co/CBsucpNm" "http://media.tumblr.com/tumblr_m65uu5UsrQ1r7h1lt.gif"]
   ["http://t.co/hyoXObbU" "http://twitpic.com/aa8rq1"]])

(?<- (stdout)
     [?url]
     (short-urls ?url))

;; RESULTS
;; -----------------------
;; http://t.co/yERArQn0
;; http://t.co/gI8TjreI
;; http://t.co/CBsucpNm
;; http://t.co/F74GG1oN
;; http://t.co/hyoXObbU
;; -----------------------

(?<- (stdout)
     [?short ?long]
     (longified-urls ?short ?long))

;; RESULTS
;; -----------------------
;; http://t.co/yERArQn0	http://news.sky.com/story/964624/olympic-lanes-open-traffic-delays-in-london
;; http://t.co/CBsucpNm	http://media.tumblr.com/tumblr_m65uu5UsrQ1r7h1lt.gif
;; http://t.co/hyoXObbU	http://twitpic.com/aa8rq1
;; -----------------------


; Outer join with ungrounded variable
(?<- (stdout)
     [?short !!long]
     (short-urls ?short)
     (longified-urls ?short !!long))

;; RESULTS
;; -----------------------
;; http://t.co/CBsucpNm	http://media.tumblr.com/tumblr_m65uu5UsrQ1r7h1lt.gif
;; http://t.co/F74GG1oN	null
;; http://t.co/gI8TjreI	null
;; http://t.co/hyoXObbU	http://twitpic.com/aa8rq1
;; http://t.co/yERArQn0	http://news.sky.com/story/964624/olympic-lanes-open-traffic-delays-in-london
;; -----------------------