diff --git a/hanafuda-webapp.cabal b/hanafuda-webapp.cabal
index b22adf0..e23e969 100644
--- a/hanafuda-webapp.cabal
+++ b/hanafuda-webapp.cabal
@@ -26,7 +26,7 @@ executable hanafudapi
                      , Config
                      , Messaging
                      , Game
-                     , Data
+                     , RW
                      , Server
                      , Session
   -- other-extensions:    
diff --git a/src/Automaton.hs b/src/Automaton.hs
index b6c18d0..9280932 100644
--- a/src/Automaton.hs
+++ b/src/Automaton.hs
@@ -4,7 +4,7 @@ module Automaton (
   ) where
 
 import Control.Monad.Reader (asks)
-import qualified Data (RW(..))
+import qualified RW (RW(..))
 import Data.Map (Map, (!?))
 import qualified Game (new, play)
 import qualified Hanafuda.KoiKoi as KoiKoi (
@@ -36,7 +36,7 @@ receive (Session.LoggedIn True) invitation@(Message.Invitation {Message.to}) = d
   case Session.status session of
     Session.LoggedIn True -> do
       from <- asks App.playerID
-      App.update_ (Server.update to (Data.set $ Session.Answering from :: Session.Update))
+      App.update_ (Server.update to (RW.set $ Session.Answering from :: Session.Update))
       Messaging.broadcast $ Messaging.update {Message.paired = [from, to]}
       (Messaging.relay invitation $ Messaging.sendTo [to])
       setSessionStatus (Session.Waiting to)
@@ -58,7 +58,7 @@ receive (Session.Answering to) message@(Message.Answer {Message.accept}) = do
           else do
             Messaging.broadcast $ Messaging.update {Message.alone = [for, to]}
             return $ Session.LoggedIn True
-      App.update_ $ Server.update to (Data.set newStatus :: Session.Update)
+      App.update_ $ Server.update to (RW.set newStatus :: Session.Update)
       setSessionStatus newStatus
     _ -> sendError "They're not waiting for your answer"
 
@@ -77,7 +77,7 @@ receive (Session.Playing gameID) played@(Message.Play {}) = do
       Messaging.notifyPlayers newGame logs
 
 receive (Session.Playing gameID) Message.Quit = do
-  games <- (Data.get <$> App.server :: App.T (Map KoiKoi.GameID KoiKoi.Game))
+  games <- (RW.get <$> App.server :: App.T (Map KoiKoi.GameID KoiKoi.Game))
   case games !? gameID of
     Nothing -> do
       playerID <- asks App.playerID
@@ -93,7 +93,7 @@ sendError = Messaging.send . Message.Error
 setSessionStatus :: Session.Status -> App.T ()
 setSessionStatus newStatus = do
   playerID <- asks App.playerID
-  App.update_ $ Server.update playerID $ (Data.set newStatus :: Session.Update)
+  App.update_ $ Server.update playerID $ (RW.set newStatus :: Session.Update)
   App.debug $ show newStatus
 
 loop :: App.T ()
diff --git a/src/Data.hs b/src/RW.hs
similarity index 93%
rename from src/Data.hs
rename to src/RW.hs
index 9e1e13a..5519911 100644
--- a/src/Data.hs
+++ b/src/RW.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
-module Data (
+module RW (
     RW(..)
   ) where
 
diff --git a/src/Server.hs b/src/Server.hs
index e9b979a..82b5755 100644
--- a/src/Server.hs
+++ b/src/Server.hs
@@ -23,7 +23,7 @@ import qualified Data.Set as Set (delete, empty, insert)
 import Data.Text (Text)
 import Hanafuda.KoiKoi (Game, GameID, PlayerID)
 import Hanafuda.Message (PlayerStatus(..), Room)
-import qualified Data (RW(..))
+import qualified RW (RW(..))
 import qualified Session (Status(..), T(..), Update)
 
 type Names = Set Text
@@ -37,19 +37,19 @@ data T = T {
     , games :: Games
   }
 
-instance Data.RW Names T where
+instance RW.RW Names T where
   get = names
   set names server = server {names}
 
-instance Data.RW Players T where
+instance RW.RW Players T where
   get = players
   set players server = server {players}
 
-instance Data.RW Sessions T where
+instance RW.RW Sessions T where
   get = sessions
   set sessions server = server {sessions}
 
-instance Data.RW Games T where
+instance RW.RW Games T where
   get = games
   set games server = server {games}
 
@@ -72,31 +72,31 @@ new = T {
     , games = Map.empty
   }
 
-register :: forall a b. (Enum a, Ord a, Data.RW (Map a b) T) => b -> T -> (T, a)
+register :: forall a b. (Enum a, Ord a, RW.RW (Map a b) T) => b -> T -> (T, a)
 register x server =
-  let playerID = maybe (toEnum 0) (\(n, _) -> succ n) $ lookupMax $ (Data.get server :: Map a b) in
-  (Data.update (insert playerID x) server, playerID)
+  let playerID = maybe (toEnum 0) (\(n, _) -> succ n) $ lookupMax $ (RW.get server :: Map a b) in
+  (RW.update (insert playerID x) server, playerID)
 
-get :: forall a b. (Ord a, Data.RW (Map a b) T) => a -> T -> b
-get playerID server = (Data.get server :: Map a b) ! playerID
+get :: forall a b. (Ord a, RW.RW (Map a b) T) => a -> T -> b
+get playerID server = (RW.get server :: Map a b) ! playerID
 
-update :: forall a b. (Ord a, Data.RW (Map a b) T) => a -> (b -> b) -> T -> T
+update :: forall a b. (Ord a, RW.RW (Map a b) T) => a -> (b -> b) -> T -> T
 update playerID updator =
-  Data.update (adjust updator playerID :: Map a b -> Map a b)
+  RW.update (adjust updator playerID :: Map a b -> Map a b)
 
 disconnect :: PlayerID -> T -> T
 disconnect playerID =
-  Data.update (delete playerID :: Sessions -> Sessions) . logOut playerID
+  RW.update (delete playerID :: Sessions -> Sessions) . logOut playerID
 
 endGame :: GameID -> T -> T
 endGame playerID =
-  Data.update (delete playerID :: Games -> Games)
+  RW.update (delete playerID :: Games -> Games)
 
 logIn :: Text -> PlayerID -> T -> Either String T
 logIn name playerID server =
-  Data.update (Set.insert name) .
-  Data.update (insert playerID name) .
-  update playerID (Data.set $ Session.LoggedIn True :: Session.Update) <$>
+  RW.update (Set.insert name) .
+  RW.update (insert playerID name) .
+  update playerID (RW.set $ Session.LoggedIn True :: Session.Update) <$>
   if name `member` names server
     then Left "This name is already registered"
     else Right server
@@ -106,7 +106,7 @@ logOut playerID server =
   maybe
     server
     (\playerName ->
-      Data.update (delete playerID :: Players -> Players) $
-      update playerID (Data.set $ Session.LoggedIn False :: Session.Update) $
-      Data.update (Set.delete playerName :: Names -> Names) server)
+      RW.update (delete playerID :: Players -> Players) $
+      update playerID (RW.set $ Session.LoggedIn False :: Session.Update) $
+      RW.update (Set.delete playerName :: Names -> Names) server)
     (players server !? playerID)
diff --git a/src/Session.hs b/src/Session.hs
index 8937543..7d61b60 100644
--- a/src/Session.hs
+++ b/src/Session.hs
@@ -9,7 +9,7 @@ module Session (
 
 import Network.WebSockets (Connection)
 import Hanafuda.KoiKoi (GameID, PlayerID)
-import qualified Data (RW(..))
+import qualified RW (RW(..))
 
 data Status =
     LoggedIn Bool
@@ -24,7 +24,7 @@ data T = T {
   }
 type Update = T -> T
 
-instance Data.RW Status T where
+instance RW.RW Status T where
   get = status
   set status session = session {status}