Improve configuration handling

src/Dodge/Config/Update.hs

@@ -0,0 +1,22 @@
+{-|
+IO actions that apply config side effects and save it to disk.
+-}
+module Dodge.Config.Update
+    where
+import Dodge.Data
+import Dodge.LoadConfig
+import Sound
+
+import Data.Aeson (encodeFile)
+import Control.Monad (when)
+
+updateDodgeConfig :: World -> IO ()
+updateDodgeConfig w = case _menuLayers w of
+    (ConfigSaveScreen _: _) -> do
+        putStrLn "Saving config"
+        encodeFile "data/dodge.config.json" cfig
+    _ -> when (_configNeedsUpdate w) $ do
+        setSoundVolume ( _volume_master cfig * _volume_sound cfig)
+        setMusicVolume ( _volume_master cfig * _volume_music cfig)
+  where
+    cfig = _config w