Clojure cinemabooker

cinemabooker.clj

(ns learningclojure.core
  (:gen-class)
  (:require [clojure.string :as str]))

(def welcome-message "
  Welcome!

  These are supported commands:
  - show
  - book <row> <col>
  - quit

  ")

(defn setup-row [] (into [] (for [_ (range 10)] "_")))

(defn setup-map []
  (into [] (for [x (range 10)]
             (setup-row))))

(defn seat-string [seat]
  (str/join ["[" seat "]"]))

(defn row-string [row]
  (str (str/join (map seat-string row)) "\n"))


(defn seat-map-string
  "Prints the current data to the screen."
  [seat-map]
  (str/join (map row-string seat-map)))

(defn book-seat [seat-map row col]
  (let
      [row-index (dec row)
       col-index (dec col)
       old-row (seat-map row-index)
       new-row (assoc old-row col-index "X")]
    (assoc seat-map row-index new-row)))

(defn ask-question [question]
    (print (str/join [question ": "]))
    (flush)
    (read-line))

(defn is-book? [answer]
  (= answer "book"))

(defn is-quit? [answer]
  (= answer "quit"))

(defn String->Number [str]
  (let [n (clojure.edn/read-string str)]
    (if (number? n) n nil)))

(defn handle-positive-action [seat-map answer]
  (let [args (str/split answer #" ")]
    (if (is-book? (args 0))
      (book-seat
       seat-map
       (String->Number (args 1))
       (String->Number (args 2)))
      (do (print (seat-map-string seat-map))
          seat-map))))

(defn -main
  [& args]
  (print welcome-message)
  (loop [seat-map (setup-map)]
    (let [answer (ask-question "Enter command")]
      (println "")
      (if-not (is-quit? answer)
        (recur (handle-positive-action seat-map answer))))))