Add frame clock

src/Dodge/Clock.hs

@@ -0,0 +1,14 @@
+module Dodge.Clock
+    ( clockCycle
+    )
+    where
+import Dodge.Data
+
+import qualified Data.Vector as V
+clockCycle :: Int -> V.Vector a -> World -> a
+{-# INLINABLE clockCycle #-}
+clockCycle tPeriod xs w = xs V.! i 
+  where
+    l = V.length xs
+    t = _frameClock w `mod` (l * tPeriod)
+    i = t `div` tPeriod