Little Clojure program that returns the winners (and each winner's earnings) of a pool.

world_cup_pool.clj

(defstruct bet :name :amount :guess :rate)
 
(defn pool-amount
  "Returns the sum of all bets' amounts."
  [poolseq]
  (reduce + (map :amount poolseq)))

(defn pool-rates
  "Returns the list of bets with their corresponding earning rates."
  [poolseq]
  (let [sum (pool-amount poolseq)]
    (map #(assoc % :rate (/ (:amount %) sum)) poolseq)))

(defn pool-winners
  "Returns the winners with their corresponding proportional earnings."
  [poolseq result]
  (let [sum (pool-amount poolseq)
        winners (filter #(= (:guess %) result) poolseq)]
    (map #(assoc % :amount (double (* (:rate %) sum))) (pool-rates winners))))

(def my-pool [(struct bet "Daniel"  2.0 [2 0])   ;; Daniel bets $2 on 2x0
              (struct bet "John"    4.0 [0 0])   ;; John bets $4 on 0x0
              (struct bet "Adriana" 1.0 [2 0])]) ;; Adriana bets $1 on 2x0

(println
  (pool-winners my-pool [2 0]))