Haskell练习

1 -- Enter your code here. Read input from STDIN. Print output to STDOUT
2 import Data.List
3 main = do
4     inputdata <- getLine
5     putStrLn . concat . map (\xs -> f (head xs) (length xs)) . group $ inputdata 
6         where 
7             f ch len
8                 | len == 1 = [ch]
9                 | otherwise = [ch] ++ show len