>>24
groupBySorted :: Ord a => [a] -> [[a]]
groupBySorted [] = []
groupBySorted (x0:xs0) = ls0 : groupBySorted rs0
　　where
　　　(ls0, rs0) = f x0 xs0
　　　f x [] = ([x], [])
　　　f x (y:ys)
　　　　　| x <= y = let (ls, rs) = f y ys in (x:ls, rs)
　　　　　| otherwise = ([x], y:ys)

main :: IO ()
main = do
　　test [8,3,4,9,9,10,6,1,4,3] -- => [[8],[3,4,9,9,10],[6],[1,4],[3]]
　　test [1,3,3,4,4,6,8,9,9,10] -- => [[1,3,3,4,4,6,8,9,9,10]]
　　test [10,9,9,8,6,4,4,3,3,1] -- => [[10],[9,9],[8],[6],[4,4],[3,3],[1]]
　　test [1,1,1,1,1,1,1,1,1,1]　-- => [[1,1,1,1,1,1,1,1,1,1]]
　　test ([] :: [Int])　　　　　-- => []
　　test [1]　　　　　　　　　　-- => [[1]]

test :: (Ord a, Show a) => [a] -> IO ()
test xs = putStrLn $ show xs ++ " => " ++ show (groupBySorted xs)