# Pastebin yS4bux1k
gridScanner :: Monoid m => Grid -> Point -> (Int -> [Int] -> m) -> m
gridScanner g p f = foldMap (f height . lookups) (scan <$> [minBound..])
  where
    height = digitToInt . Grid.b2c $ Grid.unsafeLookup g p
    scan dir = takeWhile (Grid.inRange g) . tail . iterate (fwd dir) $ p
    lookups = mapMaybe (fmap (digitToInt . Grid.b2c) . Grid.lookup g)