Count Words using Clojure - Loop and Map Reduce Way

count_words_loop.clj

(defn split-words
  [phrase]
  (clojure.string/split phrase #"\s"))

(defn count-words
  [phrase word]
  (let [words (split-words (clojure.string/lower-case phrase))
        lower-case-word (clojure.string/lower-case word)]
    (loop [head (first words)
           tail (rest words)
           sum 0]
      (if (nil? head)
        sum
        (if (= head lower-case-word)
          (recur (first tail) (rest tail) (+ sum 1))
          (recur (first tail) (rest tail) sum))))))

(count-words "Era uma Vez Bem Uma" "Uma")

count_words_map_reduce.clj

(defn split-words
  [phrase]
  (clojure.string/split phrase #"\s"))

(defn word-to-number
  [original, word]
  (if (= word original)
    1
    0))

(defn count-words
  [phrase word]
  (let [words (split-words (clojure.string/lower-case phrase))
        lower-case-word (clojure.string/lower-case word)]
    (reduce + (map (partial word-to-number lower-case-word) words))))

(count-words "Era uma Vez Bem Uma" "Uma")

count_words_recursion.clj

(defn split-words
  [phrase]
  (clojure.string/split phrase #"\s"))

(defn word-to-number
  [original word]
  (if (= word original)
    1
    0))

(defn count-items
  [items original]
  (let [head (first items)
        tail (rest items)
        match (word-to-number head, original)]
    (if (empty? tail)
      match
      (+ match (count-items tail original)))))
    
(defn count-words
  [phrase word]
  (let [words (split-words (clojure.string/lower-case phrase))
        lower-case-word (clojure.string/lower-case word)]
    (count-items words lower-case-word)))

(count-words "Era uma Vez Bem Uma" "Uma")