clojure bootcamp: "defmulti" example

src.multi-method.clj

;; inspired by suggestion in THE doc: http://java.ociweb.com/mark/clojure/article.html

(ns bootcamp.multi-method)

(defn measure-it [size]
  (cond
    (< size 3) :small
    (< size 6) :medium
    (< size 12) :large
    :else :hard-to-measure ))

(defmulti price-it measure-it)
(defmethod price-it :small [size] (str "we charge $1 for the size " size))
(defmethod price-it :medium [size] (str "we charge $2 for the size " size))
(defmethod price-it :large [size] (str "we charge $3 for the size " size))
(defmethod price-it :hard-to-measure [size] (str "size '" size "' is priceless"))

test.multi-method.clj

(ns bootcamp.test.multi-method
  (:use [bootcamp.multi-method])
  (:use [clojure.test]))

(deftest price-sizes-of-all-ranges
  (is (= (map price-it (range 0 13 4)) 
         '("we charge $1 for the size 0"
           "we charge $2 for the size 4"
           "we charge $3 for the size 8"
           "size '12' is priceless"))))