--- a/rps.erl	Tue Feb 25 23:55:18 2014 +0900
+++ b/rps.erl	Wed Feb 26 01:38:26 2014 +0900
@@ -1,25 +1,13 @@
 -module(rps).
+-import(rps3, [get_rules/0, beats/1]).
 -export([
     go/0,
-    beats/1, winner/1,
+    winner/1,
     lobby/0, counter/0, printer/0, room/1,
     fool/0, copycat/0, gambler/0]).
 
--define(RULES, [rock, paper, scissors]).
 -define(BOTS, [fool, copycat, gambler]).
 
-beats(C) ->
-    beats(C, ?RULES).
-
-beats(C, [C|Tail]) ->
-    lists:last(Tail);
-
-beats(C, [B,C|_]) ->
-    B;
-
-beats(C, [_|T]) ->
-    beats(C, T).
-
 % winner for 3 players is:
 % rock, rock, rock      -> undefined
 % rock, paper, scissors -> undefined
@@ -28,7 +16,7 @@
 
 winner(Choices) when length(Choices) > 1 ->
     CSet = sets:from_list([C || {C, _} <- Choices]),
-    RSet = sets:from_list(?RULES),
+    RSet = sets:from_list(get_rules()),
     Absents = sets:subtract(RSet, CSet),
     case sets:size(Absents) of
         1 ->
@@ -104,7 +92,7 @@
 room(Players, Choices) ->
     receive
         {Object, Who} ->
-            ObjectIsOk = lists:any(fun(X) -> X =:= Object end, ?RULES),
+            ObjectIsOk = lists:any(fun(X) -> X =:= Object end, get_rules()),
             ChoiceMade = lists:any(fun({_, Player}) -> Player =:= Who end, Choices),
             case ObjectIsOk andalso not ChoiceMade of
                 true ->
@@ -129,7 +117,7 @@
 fool(Room) ->
     receive
         start ->
-            Choice = lists:nth(random:uniform(length(?RULES)), ?RULES),
+            Choice = lists:nth(random:uniform(length(get_rules())), get_rules()),
             Room ! {Choice, self()},
             fool(Room);
         {winner, _} ->
@@ -143,7 +131,7 @@
 copycat(joined) ->
     receive
         {room, Room} ->
-            copycat(Room, hd(?RULES))
+            copycat(Room, hd(get_rules()))
     end.
 
 copycat(Room, Choice) ->
@@ -162,7 +150,7 @@
 gambler(joined) ->
     receive
         {room, Room} ->
-            Wins = dict:from_list([{C, 0} || C <- ?RULES]),
+            Wins = dict:from_list([{C, 0} || C <- get_rules()]),
             gambler(Room, Wins)
     end.
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rps3.erl	Wed Feb 26 01:38:26 2014 +0900
@@ -0,0 +1,23 @@
+-module(rps3).
+-export([get_rules/0, beats/1, test_beats/0]).
+
+get_rules() -> [rock, paper, scissors].
+
+beats(C) ->
+    beats(C, get_rules()).
+
+beats(C, [C|Tail]) ->
+    lists:last(Tail);
+
+beats(C, [B,C|_]) ->
+    B;
+
+beats(C, [_|T]) ->
+    beats(C, T).
+
+test_beats() ->
+    lists:foreach(
+        fun(C) ->
+            io:format("~w beats ~w.~n", [C, beats(C)])
+        end,
+        get_rules()).