Thread-it data

gistfile1.clj

(defmacro thread-it [& [first-expr & rest-exprs]]
  (if (empty? rest-exprs)
    first-expr
    `(let [~'it ~first-expr]
       (thread-it ~@rest-exprs))))

(def jay {:name "jay fields" :employer "drw.com" :current-city "new york"})
(def john {:name "john dydo" :employer "drw.com" :current-city "new york"})
(def mike {:name "mike ward" :employer "drw.com" :current-city "chicago"})
(def chris {:name "chris george" :employer "thoughtworks.com" :current-city "new york"})

(thread-it 
  [jay john mike chris]
  (filter (comp (partial = "new york") :current-city) it)
  (group-by :employer it)
  (update-in it ["drw.com"] (partial map :name)))

=>

{"drw.com" ("jay fields" "john dydo"),
 "thoughtworks.com"
 [{:name "chris george",
   :current-city "new york",
   :employer "thoughtworks.com"}]}