it compiles!

affection.cabal

@@ -56,7 +56,7 @@ library
                      , mtl
                      , gegl
                      , monad-loops
-                     , timeit
+                     , clock
                      -- , sdl2-image
 
 executable example00

src/Affection.hs

@@ -5,7 +5,7 @@ module Affection
     , withDefaultWindow
     , delaySec
     , module Affection.Render
-    , module Affection.Types
+    , module Types
     ) where
 
 import qualified SDL
@@ -14,7 +14,7 @@ import qualified GEGL as G
 import qualified Data.Text as T
 import Data.Maybe
 
-import System.TimeIt (timeItT)
+import System.Clock
 
 import Control.Monad.Loops
 import Control.Monad.State
@@ -31,21 +31,29 @@ withAffection conf@AffectionConfig{..} = do
       SDL.initializeAll
     Only is ->
       SDL.initialize is
-  execTime <- newMVar 0
+  execTime <- newMVar =<< getTime Monotonic
   window <- SDL.createWindow windowTitle windowConfig
   surface <- SDL.getWindowSurface window
-  let initContainer = AffectionData conf False userData window surface
+  initContainer <- return $ AffectionData
+    { affectionConfig = conf
+    , quitEvent       = False
+    , userState       = userData
+    , drawWindow      = window
+    , drawSurface     = surface
+    }
   state <- newMVar initContainer
-  (res, nState) <- runStateT (
+  (res, nState) <- runStateT ( Types.runState $
     whileM_ (do
         current <- get
         return $ Types.quitEvent current
       )
       $ do
-        lastTime <- liftIO $ fromMaybe 0 <$> tryReadMVar execTime
-        (dTime, _) <- liftIO $ timeItT <$> drawLoop
-        (uTime, _) <- liftIO $ timeItT <$> updateLoop lastTime
-        liftIO $ putMVar execTime $ lastTime + dTime + uTime
+        now      <- liftIO $ getTime Monotonic
+        lastTime <- liftIO $ fromMaybe now <$> tryReadMVar execTime
+        drawLoop
+        updateLoop $ (fromIntegral $ toNanoSecs $ diffTimeSpec lastTime now) /
+          (fromIntegral 10 ^ 9)
+        liftIO $ putMVar execTime $ now
     ) initContainer
   SDL.quit
 

src/Affection/Types.hs

@@ -2,7 +2,7 @@
 module Affection.Types
   ( AffectionData(..)
   , AffectionConfig(..)
-  -- , AffectionState(..)
+  , AffectionState(..)
   -- , AffectionDraw(..)
   -- , Draw(..)
   , AffectionStateInner(..)
@@ -30,7 +30,7 @@ data AffectionConfig us = AffectionConfig
   , windowTitle    :: T.Text                                    -- ^ Window title
   , windowConfig   :: SDL.WindowConfig                          -- ^ Window configuration
   , drawLoop       :: AffectionState (AffectionData us) IO (IO ()) -- ^ Some function. Type to be determined.
-  , updateLoop     :: Double -> AffectionState us IO (IO ())       -- ^ Another function. Type to be determined
+  , updateLoop     :: Double -> AffectionState (AffectionData us) IO (IO ())       -- ^ main update function. Takes nanoseconds as input.
   , userData       :: us
   }
 
@@ -53,12 +53,13 @@ data InitComponents
   | Only [SDL.InitFlag]
 
 -- | Inner 'StateT' monad for the update state
-type AffectionStateInner us m a = StateT (AffectionData us) m a
+-- type AffectionStateInner us m a = StateT (AffectionData us) m a
+type AffectionStateInner us m a = StateT us m a
 
 -- | Affection's state monad
 newtype AffectionState us m a = AffectionState
   { runState :: AffectionStateInner us m a }
-  deriving (Functor, Applicative, Monad, MonadIO)
+  deriving (Functor, Applicative, Monad, MonadIO, MonadState us)
 
 -- -- | Inner 'StateT' monad of Affection
 -- type AffectionInner us od a = StateT (AffectionState us od) IO a