core.clj

; The "are you thinking of an animal" game from over 2 decades ago, but in clojure

; Tim Yates

; v0.1

; Not sure if storing the brain as a load of refs is the most ideomatic way of doing things
; Also, one of my first full bits of clojure, so might not be the most sensible way of doing
; any of it

(ns animal.core
  (:gen-class))

(defn prompt [prompt-text]
  "Ask the user for some input, and keep asking till they enter something"
  (do
    (print (str prompt-text " : "))
    (flush)  
    (let [ans (read-line)]
      (if (seq ans)
        ans
	(recur prompt-text)))))

(defn yes-no [prompt-text]
  "Ask the user something, and keep asking till their answer starts with y or n"
  (let [ans (.toUpperCase (prompt (str prompt-text " [Yes/No]")))]
    (condp = (first ans)
      \Y true
      \N false
      (recur prompt-text))))

(defn new-node [text yes no]
  "Generate a new neuron in our brain"
  (ref { :text text :yes yes :no no }))

(def brain (new-node "dog" nil nil))

(defn q-and-a [neuron]
  "Walk the neurons asking questions till you reach a leaf"
  (if (nil? (:yes @neuron))
    neuron
    (if (yes-no (:text @neuron))
      (recur (:yes @neuron))
      (recur (:no @neuron)))))

(defn -main [& args]
  (while (yes-no "Are you thinking of an animal?")
    (let [synapse (q-and-a brain)]
      (if (yes-no (str "Is it a " (:text @synapse) "?"))
        (println "I Rule!")
        (let [animal (new-node (prompt "Give up! What animal were you thinking of?") nil nil)
	      quest  (prompt (str "What yes/no question would differentiate between a " (:text @animal) " and a " (:text @synapse) "?"))
	      answer (yes-no (str "For a " (:text @animal) " the answer would be?"))
	      oldani (new-node (:text @synapse) nil nil)
	      y-node (if answer animal oldani)
	      n-node (if answer oldani animal)]
	  (dosync
	    (alter synapse assoc :text quest)
	    (alter synapse assoc :yes  y-node)
	    (alter synapse assoc :no   n-node)))))))