Reading in Text File

Question

I'm trying to read in a text file using Haskell, but based on my limited and little knowledge of the language, I'm have a bit of trouble an would like some help.

I have a text file with 1000+ random words, and would like to read in the text file I know that I have to

import System.IO

and maybe

import Data.List

and I have something like this:

main = do 
       let list = []
       handle <- openFile "words.txt" ReadMode
       contents <- hGetContents handle

but I don't know much more to proceed. Any help would be great. I've been stuck for a while now and have a deadline coming soon. Thank you!

It'd be better to use the `readFile` function, you won't have to worry about file mode or handles. After reading it like `contents <- readFile "words.txt"`, you'll want to perform a transformation like `let allLines = lines contents`, then you could print it out like `print $ take 5 all_lines` — bheklilr, Feb 16 '15 at 02:22
This is almost completely identical (including the strange `let list = []` line) to a question asked a few days ago, but I can't find it now. The previous question included some goals for what to be done with the data (sort the list of words). — Cirdec, Feb 16 '15 at 03:14
see here :) http://stackoverflow.com/questions/7867723/haskell-file-reading — Sazzad, Feb 16 '15 at 03:47

score 3 · Answer 1 · answered Feb 16 '15 at 03:25

As was mentioned in the comments, the simplest way to do this is to use the readFile function. readFile is actually part of prelude (the base library), so you don't have to import anything.

contents <- readFile "words.txt" will lazily load the entire file into the string contents. Then, you can do various string processing to parse the file as you want. The function lines (included by default as well) will split the contents into a list of strings, splitting it on line breaks. The function words will split contents into a list of strings, splitting it on whitespace.

For more advanced methods, you can look into the System.IO library documention on Hackage. The documentation provided on Hackage tends to be clear and a really useful resource.

Keep up with Haskell! It's worth it.

Reading in Text File

1 Answers1