(re-seq #"s+" "Helloween")
Most common word
The collection of words is converted to lower case, so that
the are not counted as separate words.
frequencies returns a collection of tuples, each tuple being a word and a value representing how often it occurs. This collection is sorted by the value in descending order to show the word with the most occurrences at the top.
(->> (slurp "http://www.gutenberg.org/cache/epub/844/pg844.txt") (re-seq #"[a-zA-Z0-9|']+") (map #(clojure.string/lower-case %)) frequencies (sort-by val dec))