[Haskell-beginners] Too much mapM, fmap and concat

[martin]

Hello all,

I never did much IO in haskell, but now I have to process some files. I catch myself adding a mapM here and an fmap
there. While it is clear to me what these functions do, I wonder if there is a way to avoid the noise. Also I could not
find a simple way to pair the lines of a file with its filename. I ended up writing a function "nameAndContent". Finally
I am amazed by the many "concat"s I need.

Maybe these things just lie in the nature of the problem ("process a number of files"). Otherwise any style suggestions
would be much appreciated.

import System.FilePath.Glob
import Data.List

filePattern="*.hs"
fileDirectory = "."

processFile :: (FilePath, [String]) -> [String]
processFile (path, flines) = ["done"]

main = do
    matchingFiles <- fmap (concat . fst) $ globDir [compile filePattern] fileDirectory
    flines <- mapM nameAndContent matchingFiles
    result <- mapM (return . processFile) flines
    mapM putStrLn $ concat  result
            where
                nameAndContent :: FilePath -> IO (FilePath, [String])
                nameAndContent fn = do
                    content <- fmap lines $ readFile fn
                    return (fn, content)