xmonad-config/lib/Xmobar/Plugins/BacklightCommon.hs

-- Common backlight plugin bits
--
-- Use the custom DBus interface exported by the XMonad process so I can react
-- to signals spawned by commands
module Xmobar.Plugins.BacklightCommon (startBacklight) where

import Data.Internal.DBus
import RIO
import qualified RIO.Text as T
import Xmobar.Plugins.Common

startBacklight
  :: (MonadUnliftIO m, RealFrac a)
  => Maybe FilePath
  -> ((Maybe a -> DIO SimpleApp SesClient ()) -> DIO SimpleApp SesClient ())
  -> DIO SimpleApp SesClient (Maybe a)
  -> T.Text
  -> Callback
  -> m ()
startBacklight name matchSignal callGetBrightness icon cb = do
  withDBusClientConnection cb name $ \c -> withDIO c $ do
    matchSignal dpy
    dpy =<< callGetBrightness
  where
    formatBrightness b = return $ T.concat [icon, T.pack $ show (round b :: Integer), "%"]
    dpy = displayMaybe cb formatBrightness