REF clean up state functions in bluetooth

lib/Xmobar/Plugins/Bluetooth.hs

@@ -157,6 +157,11 @@ readState = do
   c <- readDevices
   return (p, anyDevicesConnected c)
 
+modifyState :: (BtState -> BTIO (BtState, a)) -> BTIO a
+modifyState f = do
+  m <- asks btState
+  modifyMVar m f
+
 --------------------------------------------------------------------------------
 -- Object manager
 
@@ -281,9 +286,7 @@ callGetPowered adapter =
       T.unpack adaptorPowered
 
 putPowered :: Maybe Bool -> BTIO ()
-putPowered ds = do
-  m <- asks btState
-  modifyMVar_ m (\s -> return s {btPowered = ds})
+putPowered ds = modifyState $ \s -> return (s {btPowered = ds}, ())
 
 readPowered :: BTIO (Maybe Bool)
 readPowered = fmap btPowered $ readMVar =<< asks btState
@@ -334,28 +337,22 @@ callGetConnected p =
     memberName_ (T.unpack devConnected)
 
 insertDevice :: ObjectPath -> BTDevice -> BTIO Bool
-insertDevice device dev = do
-  m <- asks btState
-  modifyMVar m $ \s -> do
-    let new = M.insert device dev $ btDevices s
-    return (s {btDevices = new}, anyDevicesConnected new)
+insertDevice device dev = modifyState $ \s -> do
+  let new = M.insert device dev $ btDevices s
+  return (s {btDevices = new}, anyDevicesConnected new)
 
 updateDevice :: ObjectPath -> Maybe Bool -> BTIO Bool
-updateDevice device status = do
-  m <- asks btState
-  modifyMVar m $ \s -> do
-    let new = M.update (\d -> Just d {btDevConnected = status}) device $ btDevices s
-    return (s {btDevices = new}, anyDevicesConnected new)
+updateDevice device status = modifyState $ \s -> do
+  let new = M.update (\d -> Just d {btDevConnected = status}) device $ btDevices s
+  return (s {btDevices = new}, anyDevicesConnected new)
 
 anyDevicesConnected :: ConnectedDevices -> Bool
 anyDevicesConnected = or . mapMaybe btDevConnected . M.elems
 
 removeDevice :: ObjectPath -> BTIO (Maybe BTDevice)
-removeDevice device = do
-  m <- asks btState
-  modifyMVar m $ \s -> do
-    let devs = btDevices s
-    return (s {btDevices = M.delete device devs}, M.lookup device devs)
+removeDevice device = modifyState $ \s -> do
+  let devs = btDevices s
+  return (s {btDevices = M.delete device devs}, M.lookup device devs)
 
 readDevices :: BTIO ConnectedDevices
 readDevices = fmap btDevices $ readMVar =<< asks btState