How do I clear the terminal screen in Haskell?

Question

How can I clear a terminal screen after my user has selected an option from my application's menu?

Can you be more clear about what user interface system you are using in your Haskell program? Do you mean that you are simply reading and writing text to stdin/stdout? If so, those have no implicit concept of "screen". If you intend your program to work assuming that there is a terminal attached to stdin/stdout, then you should be coding your program to use some terminal control package, such as indicated @ZackS' answer. — MtnViewMark, Mar 19 '10 at 05:07
Please choose the correct answer. People have to go through all answers! — Shishir Gupta, Aug 24 '16 at 14:01

score 221 · Answer 1 · edited Apr 15 '15 at 08:22

221

:! run the shell command
:! cls under windows
:! clear under linux and OS X

edited Apr 15 '15 at 08:22

lol

3,910
2
37
40

answered Feb 18 '12 at 23:29

void

2,267
1
13
2

2

is there any cheatsheet for ghci? – tugberk Jun 22 '14 at 14:51
2

@Peter my best guess is it's because they don't think it's a haskell solution (rightfully so; it only works in GHCi), it doesn't work for them (shell-dependent) or they just consider ZachS' answer a better one. `:! cls` is plenty sufficient for my use case but doesn't work for the asker's case as the asker isn't using GHCi. – John Dvorak Jun 29 '15 at 08:58
Just what I was looking for, thank you for this. – nlhnt Aug 07 '23 at 13:54

score 63 · Answer 2 · answered Mar 18 '10 at 18:53

63

This is what you may be looking for:

ansi-terminal: Simple ANSI terminal support, with Windows compatibility

You can find it in Hackage and install using cabal install ansi-terminal. It specifically has functions for clearing the screen, displaying colors, moving the cursor, etc.

Using it to clear the screen is easy: (this is with GHCI)

import System.Console.ANSI clearScreen

answered Mar 18 '10 at 18:53

ZachS

1,238
7
11

4

This is the correct answer. Try to look for the package in your system’s package manager though, as cabal generally doesn’t work with that and doesn’t offer an uninstall command. – Evi1M4chine Mar 21 '14 at 05:03

score 21 · Answer 3 · answered May 24 '17 at 07:17

21

Just press Ctrl+L (works on Windows)

answered May 24 '17 at 07:17

mitaness

695
7
13

3

Works on macOS too – oluckyman Aug 25 '17 at 05:18
1

Works on ubuntu + zsh as well. – Tejaswi Yerukalapudi Dec 19 '19 at 02:18

score 18 · Answer 4 · answered Feb 20 '12 at 10:53

On a terminal that understands ANSI escape sequences (I believe every term in Unix/Linux systems) you can do it simply with:

clear = putStr "\ESC[2J"

The 2 clears the entire screen. You can use 0 or 1 respectively if you want to clear from the cursor to end of screen or from cursor to the beginning of the screen.

However I don't think this works in the Windows shell.

score 9 · Answer 5 · edited Jun 09 '21 at 20:39

9

On Unix systems you can do System.system "clear" which just invokes the command-line utility clear. For a solution that does not depend on external tools, you'd need a library that abstracts over different terminal-types like for example ansi-terminal.

edited Jun 09 '21 at 20:39

Farbod Salamat-Zadeh

19,687
20
75
125

answered Mar 18 '10 at 18:35

sepp2k

363,768
54
674
675

8

@Pradeep: Yes, and I answered in haskell. – sepp2k Mar 18 '10 at 18:41
8

@Pradeep: No need to shout. (See http://en.wikipedia.org/wiki/All_caps#Internet ) – Jared Updike Mar 18 '10 at 18:57

score 9 · Answer 6 · answered Jul 18 '18 at 16:12

9

On Windows, use Ctrl + L for Haskell command prompt terminal. And, for GUI use Ctrl + S.

answered Jul 18 '18 at 16:12

Shuvam Shah

357
2
6
13

score 7 · Answer 7 · answered Feb 12 '13 at 15:23

7

A quick way on Windows would be to

import System.Process

clear :: IO ()
clear = system "cls"

answered Feb 12 '13 at 15:23

Boris

5,094
4
45
71

This was the cleanest solution for me, and for Linux systems use `system "clear`. – Iain J. Reid Mar 07 '20 at 14:36

score 0 · Answer 8 · answered May 11 '17 at 12:07

0

Under Linux (Ubuntu at least), that's the code I use for clearing the terminal:

import qualified System.Process as SP

clearScreen :: IO ()
clearScreen = do
  _ <- SP.system "reset"
  return ()

answered May 11 '17 at 12:07

Stephane Rolland

38,876
35
121
169

How do I clear the terminal screen in Haskell?

8 Answers8

Linked