Add options page scrolling

src/Dodge/Base/Collide.hs

@@ -48,6 +48,7 @@ import FoldableHelp
 import Data.Maybe
 import qualified Data.IntMap.Strict as IM
 import Control.Lens
+import Control.Monad
 import qualified FoldlHelp as L
 import Data.Monoid
 import Streaming
@@ -149,19 +150,17 @@ orderStreamOn f = S.each . runIdentity . L.purely S.fold_ L.map . S.map g
   where
     g x = (f x,x)
 
-visibleWallWalls :: Point2 -> Point2 -> World -> Stream (Of (Point2,Wall)) Identity ()
-visibleWallWalls sp ep = 
-    join
-    . fmap (S.take 1)
-    . S.span (not . wlIsOpaque . snd)
+visibleWalls :: Point2 -> Point2 -> World -> Stream (Of (Point2,Wall)) Identity ()
+visibleWalls sp ep = S.take 1 <=<  -- hlint, was using join and fmap
+    ( S.span (not . wlIsOpaque . snd)
     . orderStreamOn (dist sp . fst)
     . S.mapMaybe f
-    . wallsAlongLineStream sp ep
+    . wallsAlongLineStream sp ep    )
   where
     f wl = uncurry (intersectSegSeg sp ep) (_wlLine wl) <&> (,wl)
 
 allVisibleWalls :: World -> Stream (Of (Point2,Wall)) Identity ()
-allVisibleWalls w = concats $ S.subst (flip (visibleWallWalls vPos) w . (+.+ vPos)) $ S.each (nRays 20)
+allVisibleWalls w = concats $ S.subst (flip (visibleWalls vPos) w . (+.+ vPos)) $ S.each (nRays 20)
   where
     vPos = _cameraViewFrom w