Hello Awsaf,

you should probably look further into the topic of "IO in Haskell" and "Monads". Then you can use impure functions like readFile (http://hackage.haskell.org/package/base-4.11.1.0/docs/Prelude.html#v:readFile ) or getArgs (http://hackage.haskell.org/package/base-4.11.1.0/docs/System-Environment.html#v:getArgs). A naive solution might look like this:

module Main where

import System.Environment (getArgs)

main = do

(fileName:_) <- getArgs

unsortedList <- read <$> readFile fileName

let sorted = yourMergeSortFunction unsortedList

print sorted -- maybe you like to print your sorted list

Best regards,
Tobias

----- Nachricht von Awsaf Rahman <awsafrahman1704@gmail.com> ---------
Datum: Thu, 5 Jul 2018 22:21:15 +0200
Von: Awsaf Rahman <awsafrahman1704@gmail.com>
Antwort an: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell <beginners@haskell.org>
Betreff: [Haskell-beginners] Passing a file containing a list as an input
An: beginners@haskell.org

Hello everyone!

I am really struggling with Haskell I/O.

I have written a mergesort program and as an input to that program I want to use a file containing a list of 1000 integers. Let's say the contents of the file look like this

[120, 400, 500 , 20, 100 ..]

How can I achieve that? I am trying to write a main function that takes the file as an input and passes the list to my mergesort function..

Regards

Awsaf Rahman

----- Ende der Nachricht von Awsaf Rahman <awsafrahman1704@gmail.com> -----