gistfile1.clj

;; "Clojure transactions should be easy to understand if you've ever used database
;; transactions - they ensure that all actions on Refs are atomic, consistent, and 
;; isolated."  (http://clojure.org/refs)

(def large-future-data-structure (ref {}))

(def big-text (read-lines (File. "/path/to/my/file")))

;; #"" is how you define a regex
;; dosync is required for transactions with a ref
(defn add-to-structure [line]
  (let [match (re-match #"foo" line)]
    (dosync
      (if match (conj match large-future-data-structure)))))

;; (fn [x]) can be replaced with the syntactic sugar: #(%)
;; as in: (map #(inc %) [1 2 3 4]) => [2 3 4 5]
;; or: (map #(+ % %) [1 2 3 4]) => [2 4 6 8]

(.start (Thread. (fn [] (map add-to-structure big-text))))