refactor(xan): Switch to V2 over tuples most places

These are generally rather nicer to work due to some typeclass instances,
and integrate better with other ecosystems for things like linear
algebra etc.

Change-Id: I546c8da7b17234648f3d612b28741c1fded25447
Reviewed-on: https://cl.tvl.fyi/c/depot/+/910
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>

users/glittershark/xanthous/src/Xanthous/Generators.hs

@@ -39,6 +39,7 @@ import           Xanthous.Entities.Environment
 import           Xanthous.Entities.Item (Item)
 import           Xanthous.Entities.Creature (Creature)
 import           Xanthous.Game.State (SomeEntity(..))
+import           Linear.V2
 --------------------------------------------------------------------------------
 
 data Generator
@@ -91,18 +92,18 @@ parseGeneratorInput = Opt.subparser
 
 showCells :: Cells -> Text
 showCells arr =
-  let ((minX, minY), (maxX, maxY)) = bounds arr
+  let (V2 minX minY, V2 maxX maxY) = bounds arr
       showCellVal True = "x"
       showCellVal False = " "
       showCell = showCellVal . (arr !)
-      row r = foldMap (showCell . (, r)) [minX..maxX]
+      row r = foldMap (showCell . (`V2` r)) [minX..maxX]
       rows = row <$> [minY..maxY]
   in intercalate "\n" rows
 
 cellsToWalls :: Cells -> EntityMap Wall
 cellsToWalls cells = foldl' maybeInsertWall mempty . assocs $ cells
   where
-    maybeInsertWall em (pos@(x, y), True)
+    maybeInsertWall em (pos@(V2 x y), True)
       | not (surroundedOnAllSides pos) =
         let x' = fromIntegral x
             y' = fromIntegral y