[Haskell-beginners] Reading Multiple Files and Iterate Function Application

[Lorenzo Isella]

Dear All,
Another I/O question.
Let us say that you are given a list of files file1.dat, 
file2.dat...file10.dat and so on (i.e. every file is indexed by a number 
and every file is a single column where every entry is a string without 
spaces).
In the snippet below I read file1.dat, convert it to a list and then 
print out its length.
Now, how can I iterate the process on file1.dat, file2.dat and file3.dat 
and store the lengths in a list?
I would like to map the file reading and following operations on the 
list [1,2.3], but that is giving me a headache.
It is relatively easy to create the file name

filename="file"++(show i)++".dat"   , for i=1,2,3

but it the the iteration part that is giving me troubles.
Any suggestion is appreciated.
Cheers

Lorenzo



-- #####################################################################

import Data.Ord


import Data.List

main :: IO ()

main = do

   list_t <- readFile "file1.dat"


   let list = lines list_t

   let b = length list

   putStrLn "length of list is, "
   print b