Question

I’m trying to write a urlview clone in Haskell. The program reads a message (piped via STDIN), extracts all URLs and asks the user to select one of them.

After reading the message, STDIN obviously reaches EOF. In Python, I reset STDIN like this

message = sys.stdin.read()
sys.stdin = open('/dev/tty')
selected_index = raw_input('Which URL to open? ')

How would I achieve the same in Haskell?

Answer 1

As far as I know there is no way to “re-assign” the built-in stdin in Haskell, but you can otherwise open a new handle to /dev/tty. A direct translation of your Python code would be something like

import System.IO

main = do
    message <- getContents
    tty <- openFile "/dev/tty" ReadMode
    putStr "Which URL to open? "
    url <- hGetLine tty
    ...