Start using streaming as the way to consume foldable objects

src/Geometry/Zone.hs

@@ -3,9 +3,12 @@ module Geometry.Zone
     ( ddaExt
     , ddaExt'
     , ddaSq
+    , ddaSqStream
     ) where
 import Geometry.Data
 
+import Streaming
+import qualified Streaming.Prelude as S
 import Data.Foldable
 import qualified Data.IntMap.Strict as IM
 import qualified Data.IntSet as IS
@@ -89,6 +92,14 @@ ddaSq s (V2 sx sy) (V2 ex ey) = IM.fromSet (const ys) xs
     xs = IS.fromDistinctAscList [minx-1..maxx+1]
     ys = IS.fromDistinctAscList [miny-1..maxy+1]
 
+ddaSqStream :: Monad m => Float -> V2 Float -> V2 Float -> Stream (Of (Int,Int)) m ()
+ddaSqStream s (V2 sx sy) (V2 ex ey) = S.each [(x,y) | x <- [minx..maxx], y <- [miny..maxy]]
+  where
+    maxMin a b | a >= b = (a,b)
+        | otherwise = (b,a)
+    (maxx,minx) = maxMin (divTo s sx) (divTo s ex)
+    (maxy,miny) = maxMin (divTo s sy) (divTo s ey)
+
 -- | Determines which horizontal and vertical lines on a grid are crossed by a
 -- line. For each adds the x-y index of the square to the right or above the
 -- crossed grid line. Also adds the index of the square containing the start