most_common_word.clj

;; Book: The importance of being Earnest, Oscar Wilde
;; Source: Project Guttenburg (UTF-8 format)
(def importance-of-being-earnest
  (slurp "http://www.gutenberg.org/cache/epub/844/pg844.txt"))

(def common-english-words
  (set
   (clojure.string/split
    (slurp
     "http://www.textfixer.com/resources/common-english-words.txt")
    #",")))

(defn most-common-words [book]
  (reverse
   (sort-by val
    (frequencies
     (remove common-english-words
      (map
        #(clojure.string/lower-case %)
        (re-seq #"[a-zA-Z0-9|']+" book)))))))

(most-common-words importance-of-being-earnest)