beer_song.clj

(ns beer-song 
  (:require [clojure.string :as string]))
(require '[clojure.core.match :refer [match]])

;; 2 bottles of beer on the wall, 2 bottles of beer.
;; Take one down and pass it around, 1 bottle of beer on the wall.

;; 1 bottle of beer on the wall, 1 bottle of beer.
;; Take it down and pass it around, no more bottles of beer on the wall.

;; No more bottles of beer on the wall, no more bottles of beer.
;; Go to the store and buy some more, 99 bottles of beer on the wall.

(def part1 " of beer on the wall, ")
(def part2 " of beer.\n")
(def part3 " down and pass it around, ")
(def part4 " of beer on the wall.\n")

(defn verse
  "Returns the nth verse of the song."
  [num] (match num
          0 (str "No more bottles" part1 "no more bottles" part2 "Go to the store and buy some more, 99 bottles" part4)
          1 (str "1 bottle" part1 "1 bottle" part2 "Take it" part3 "no more bottles" part4)
          n (str n " bottles" part1 n " bottles" part2 "Take one" part3 (- n  1) (if (= n 2) " bottle" " bottles") part4) 
  )
)

(defn sing
  "Given a start and an optional end, returns all verses in this interval. If
  end is not given, the whole song from start is sung."
  ([start] (sing start 0))
  ([start end] (string/join "\n" (map verse (reverse (range end (+ start 1))))))
)