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Rock Paper Scissors with core.async
(require 'clojure.core.async :refer :all)
(def MOVES [:rock :paper :scissors])
(def BEATS {:rock :scissors, :paper :rock, :scissors :paper})
(defn rand-player
"Create a named player and return a channel to report moves."
(let [out (chan)]
(go (while true (>! out [name (rand-nth MOVES)])))
(defn winner
"Based on two moves, return the name of the winner."
[[name1 move1] [name2 move2]]
(= move1 move2) "no one"
(= move2 (BEATS move1)) name1
:else name2))
(defn judge
"Given two channels on which players report moves, create and return an
output channel to report the results of each match as [move1 move2 winner]."
[p1 p2]
(let [out (chan)]
(while true
(let [m1 (<! p1)
m2 (<! p2)]
(>! out [m1 m2 (winner m1 m2)]))))
(defn init
"Create 2 players (by default Alice and Bob) and return an output channel of match results."
([] (init "Alice" "Bob"))
([n1 n2] (judge (rand-player n1) (rand-player n2))))
(defn report
"Report results of a match to the console."
[[name1 move1] [name2 move2] winner]
(println name1 "throws" move1)
(println name2 "throws" move2)
(println winner "wins!"))
(defn play
"Play by taking a match reporting channel and reporting the results of the latest match."
(apply report (<!! out-chan)))
(defn play-many
"Play n matches from out-chan and report a summary of the results."
[out-chan n]
(loop [remaining n
results {}]
(if (zero? remaining)
(let [[m1 m2 winner] (<!! out-chan)]
(recur (dec remaining)
(merge-with + results {winner 1}))))))
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