Hello,

I'm wondering if it is possible doing IO in terms of Arrow.

I got a function search all files under directory recursively and I'd like to refartoring using Arrow terms.

I tried to define a function like below but failed.

isDirExist = Kleisli doesDirectoryExist

Do I need to define a instance for IO to be Arrow? Or is there any existing solutions?

I'm a newbie of Haskell and thanks your help.

~~~~~

getFilesInDir :: FilePath -> IO [FilePath]

getFilesInDir inp = do

isDir <- doesDirectoryExist inp

files <- if isDir then

(do

names <- getDirectoryContents inp

forM [ inp </> x | x <- names, isNotSpecialDir x ] getFilesInDir)

else return [[inp]]

return $ concat files

~~~~~