My xmonad.hs:

import XMonad

main = xmonad defaultConfig
         { modMask = mod4Mask
         , terminal = "xterm"
         }

but after restart xmonad I get the following error message

Error detected while loading xmonad configuration file: /home/yuliang/.xmonad/xmonad.hs

xmonad.hs:1:7:
    Could not find module `XMonad':
      it is a member of the hidden package `xmonad-0.9'
      Use -v to see a list of the files searched for.

Please check the file for errors.

--
Sincerely,
Yuliang Wang