Question

I’m a Haskell beginner and I’m using xmonad. I’m trying to make it prompt me before quitting as I occasionally hit mod+q by accident. I’ve found two ways of doing that, but I must be doing something wrong because neither of them work for me:
https://bbs.archlinux.org/viewtopic.php?id=120298
http://comments.gmane.org/gmane.comp.lang.haskell.xmonad/11699

Here’s my xmonad.hs:

import XMonad
import XMonad.Config.Gnome
import XMonad.Actions.Plane
import XMonad.Util.EZConfig
import XMonad.Util.Run(spawnPipe)
import qualified Data.Map as M
import XMonad.Hooks.DynamicLog
import XMonad.Hooks.ManageDocks
import XMonad.Hooks.UrgencyHook
import System.IO(Handle, hPutStrLn)
import System.Exit
import Control.Monad
import XMonad
import XMonad.Util.EZConfig
import XMonad.Util.Dmenu
import XMonad.Util.Run

workspaces' = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "0"]

quit_confirm :: X ()
quit_confirm = do
  let m = "confirm restart"
  s <- dmenu [m]
  when (m == s) (spawn "xmonad --restart")

conf_quit = do
  response <- runProcessWithInput "dmenu" ["-p", "Quit?"] "yes\nno\n"
  when (response == "yes") (spawn "xmonad --restart")

main = do
        dzen2Pipe <- spawnPipe "dzen2 -w 1200 -xs 1 -ta l -fn '-*-terminus-*-*-*-*-16-*-*-*-*-*-*-*' -bg black -fg #d3d7cf "
        dzen2Right <- spawnPipe "~/.xmonad/status-dzen.sh"
        startupProgs <- spawnPipe "~/.xmonad/startups.sh"
        xmonad $ defaultConfig
             {
             workspaces = workspaces'
             , manageHook = manageHook' <+> manageHook defaultConfig
             , modMask = mod4Mask
             , terminal = "gnome-terminal"
     , layoutHook = layoutHook'
         , logHook = logHook' dzen2Pipe
             }
            `additionalKeysP`
               [ -- Lock Screen
                ("M-S-l",    spawn "gnome-screensaver-command -l")
                -- Sleep
                , ("M-S-;",   spawn "gnome-screensaver-command -l; pmi action suspend")
                -- wireless
                , ("M-S-C-w", spawn "~/.xmonad/wireless.sh")
                -- 1 screen reconf
                , ("M-S-C-1", spawn "~/.xmonad/1-screen.sh")
                -- 2 screen reconf
                , ("M-S-C-2", spawn "~/.xmonad/2-screen.sh")
                -- confirm for quit
                , ("M-q", conf_quit)
                ]
             `additionalKeys`
             M.toList (planeKeys mod4Mask GConf Finite)

layoutHook' = avoidStruts $ layoutHook defaultConfig

logHook' = dynamicLogWithPP . dzenPP'

dzenPP' h = defaultPP
            {
            ppOutput = hPutStrLn h
            }

manageHook' = composeAll
  [ className =? "Pidgin" --> doShift "1" ,
    className =? "Firefox" --> doShift "2" ,
    className =? "Thunderbird" --> doShift "3" ,
    className =? "OpenOffice.org 3.2" --> doShift "4",
    manageDocks ]

Thanks!

Edit: the menu is displayed, but spawn process doesn’t seem to work.

Answer 1

The answers others gave missed that dmenu seems to add an extra whitespace to the end of the string it returns. You just need to do the following and it works for me:

confirm :: String -> X () -> X ()
confirm m f = do
  result <- dmenu [m]
  when (init result == m) f

And then, as @mariop suggested use either

confirm "Restart" $ spawn "xmonad --recompile && xmonad --restart"

or

confirm "Exit" $ io (exitWith ExitSuccess)