Cleanup: broken pathfinding

src/Padding.hs

@@ -7,6 +7,7 @@ module Padding
     , rotU
     , rotD
     , rotListAt
+    , insertAt
     )
     where
 leftPad :: Int -> a -> [a] -> [a]
@@ -46,3 +47,6 @@ rotListAt x' xs = f x' xs []
         | y == x    = y:ys ++ zs
         | otherwise = f x ys (y:zs)
     f _ [] zs = zs
+
+insertAt :: Int -> a -> [a] -> [a]
+insertAt i x xs = let (ys,zs) = splitAt i xs in ys ++ [x] ++ zs