Make pictures use Streaming

src/Dodge/Render/List.hs

@@ -6,6 +6,7 @@ import Picture
 import Geometry
 --import Control.Monad
 import Data.Maybe
+import Data.Foldable
 
 -- given a list of pictures that are each the size of a "text" call, displays them as
 -- a list on the screen
@@ -30,7 +31,7 @@ listCursorChooseBorder borders xoff yoff cfig yint col cursxsize cursysize = win
     hgt = 20 * fromIntegral cursysize
 -- note we cannot simply scale lines because they are drawn as solid rectangles
 chooseCursorBorders :: Float -> Float -> [Bool] -> Picture
-chooseCursorBorders wth hgt = concat . catMaybes . zipWith f
+chooseCursorBorders wth hgt = fold . catMaybes . zipWith f
     [ line [V2   0 hgt , V2 wth hgt ] 
     , line [V2 wth hgt , V2 wth   0 ] 
     , line [V2 wth   0 , V2   0   0 ]