rendezvous with cassidoo challenge: 23.03.27

roll_dice.clj

(ns roll-dice
  (:require 
   [clojure.string :as string]
   [clojure.test :refer [deftest is]))

(defn roll-dice [dice-str]
  (let [roll-die (fn [die-size]
                   (inc (rand-int die-size)))]
    (->> (string/split dice-str #"\+") ;; ["1d8" "2d10"]
         (map #(string/split % #"d"))  ;; (["1" "8"] ["2" "10"])
         (map #(map parse-long %))     ;; ((1 8) (2 10))
         (mapcat (fn [[n size]]
                   (repeatedly n #(roll-die size))))
         (reduce + 0))))

(deftest roll-dice-test
  (is (<= 4 (roll-dice "4d4") 16))
  (is (<= 3 (roll-dice "3d20") 60))
  (is (<= 3 (roll-dice "1d8+2d10") 28)))

(comment
  (repeatedly 5 #(roll-dice "4d4"))      ;; (8 11 15 14 8)
  (repeatedly 5 #(roll-dice "3d20"))     ;; (30 14 39 30 29)
  (repeatedly 5 #(roll-dice "1d8+2d10")) ;; (13 22 25 19 19)
  ,)