Setup for overlap routing

yesod-routes/Yesod/Routes/Overlap.hs

@@ -0,0 +1,41 @@
+-- | Check for overlapping routes.
+module Yesod.Routes.Overlap
+    ( findOverlaps
+    , findOverlapNames
+    ) where
+
+import Yesod.Routes.TH.Types
+import Control.Arrow ((***))
+
+findOverlaps :: [Resource t] -> [(Resource t, Resource t)]
+findOverlaps = undefined
+
+findOverlapNames :: [Resource t] -> [(String, String)]
+findOverlapNames = map (resourceName *** resourceName) . findOverlaps
+
+{-
+-- n^2, should be a way to speed it up
+findOverlaps :: [Resource a] -> [[Resource a]]
+findOverlaps = go . map justPieces
+  where
+    justPieces :: Resource a -> ([Piece a], Resource a)
+    justPieces r@(Resource _ ps _) = (ps, r)
+
+    go [] = []
+    go (x:xs) = mapMaybe (mOverlap x) xs ++ go xs
+
+    mOverlap :: ([Piece a], Resource a) -> ([Piece a], Resource a) ->
+                Maybe [Resource a]
+    mOverlap _ _ = Nothing
+                {- FIXME mOverlap
+    mOverlap (Static x:xs, xr) (Static y:ys, yr)
+        | x == y = mOverlap (xs, xr) (ys, yr)
+        | otherwise = Nothing
+    mOverlap (MultiPiece _:_, xr) (_, yr) = Just (xr, yr)
+    mOverlap (_, xr) (MultiPiece _:_, yr) = Just (xr, yr)
+    mOverlap ([], xr) ([], yr) = Just (xr, yr)
+    mOverlap ([], _) (_, _) = Nothing
+    mOverlap (_, _) ([], _) = Nothing
+    mOverlap (_:xs, xr) (_:ys, yr) = mOverlap (xs, xr) (ys, yr)
+    -}
+-}