Add (persistent) volume control

src/Dodge/Config/Data.hs

@@ -0,0 +1,39 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE StrictData #-}
+module Dodge.Config.Data (
+      Configuration (..)
+    , defaultConfig
+    , volume_master
+    , volume_sound
+    , volume_music
+    ) where
+
+import Data.Aeson
+import Foreign.C.Types
+import GHC.Generics
+import qualified GHC.Int
+import qualified SDL
+import System.Directory
+import Control.Lens
+
+data Configuration = Configuration
+  { _volume_master   :: Float
+  , _volume_sound    :: Float
+  , _volume_music    :: Float
+  }
+  deriving (Generic, Show)
+
+makeLenses ''Configuration
+
+instance ToJSON Configuration where
+  toEncoding = genericToEncoding defaultOptions
+
+instance FromJSON Configuration
+
+defaultConfig = Configuration
+    { _volume_master = 1
+    , _volume_sound  = 1
+    , _volume_music  = 1
+    }
+