Replicate

gistfile1.txt

module Main where

import Control.Monad

main :: IO ()
main = do putStrLn "Enter the amount of line to read"
          s <- readLn :: IO Int
          putStrLn ("Now enter " ++ show s ++ " lines ")
          elements <- replicateM s getLine
          let result = doSomething elements
          print result
          return ()

doSomething :: [String] -> [String]
doSomething = map (++ "_operation on element")

Total version:

module Main where

import Control.Monad
import Text.Read

main :: IO ()
main = do putStrLn "Enter the amount of line to read"
          s <- readNumber
          case s of
              Just num -> inputLine num
              Nothing -> putStrLn "Not a valid number"
          return ()

inputLine :: Int -> IO ()
inputLine s = do putStrLn ("Now enter " ++ show s ++ " lines ")
                 elements <- replicateM s getLine
                 let result = doSomething elements
                 print result


readNumber :: IO (Maybe Int)
readNumber = do s <- getLine
                let a = readMaybe s :: Maybe Int
                return a

doSomething :: [String] -> [String]
doSomething = map (++ "_operation on element")