Fix warning.

examples/knock_knock.hs

@@ -3,19 +3,20 @@
 {-# LANGUAGE OverloadedStrings #-}
 module Main(main) where
 
-import Reanimate
-import Reanimate.Builtin.Documentation
-import Reanimate.Scene
-import Reanimate.LaTeX
-import Control.Lens
-import Control.Monad
+import           Control.Lens
+import           Control.Monad
+import           Data.Text                       (Text)
+import           Reanimate
+import           Reanimate.Animation             (Duration)
+import           Reanimate.Builtin.Documentation
+import           Reanimate.LaTeX
+import           Reanimate.Scene
 
 main :: IO ()
 main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
   line1 <- newLaTeX ["$>$ ", "knock!", " ", "knock!"]
-  forM_ line1 $ \o ->
-    oModify o $
-      oTopY .~ (screenHeight/2)
+  oModifyMany line1 $
+    oTopY .~ screenTop
 
   oFadeIn (line1!!0) 1
   oShow (line1!!1); wait 0.3
@@ -26,7 +27,7 @@ main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
 
   oFadeIn (line2!!0) 1
   oDraw (line2!!1) 1
-  
+
   line3 <- newLaTeX ["$>$ ", "$(\\lambda x . x)$"]
   mapM_ (`placeBelow` head line2) line3
 
@@ -48,13 +49,22 @@ main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
 
   wait 1
 
+screenTop :: Double
+screenTop = screenHeight/2
+
+oModifyMany :: [Object s a] -> (ObjectData a -> ObjectData a) -> Scene s ()
+oModifyMany os m = forM_ os $ \o -> oModify o m
+
+placeBelow :: Object s a -> Object s b -> Scene s ()
 placeBelow a b = do
   bBot <- oRead b oBottomY
   oModify a $
     oTopY .~ bBot
 
+newLaTeX :: [Text] -> Scene s [Object s SVG]
 newLaTeX chunks = mapM newObject $ map (translate (-4) 0) $ latexChunks chunks
 
+oDraw :: Object s a -> Duration -> Scene s ()
 oDraw o d = do
   oShow o
   oTweenS o d $ \t ->