[xmonad] XMonad.Prompt.Workspace error

I copied the following lines from XMonad.Prompt.Workspace usage: import XMonad.Prompt import XMonad.Prompt.Workspace , ((modMask x .|. shiftMask, xK_m ), workspacePrompt defaultXPConfig (windows . W.shift)) but when I reload xmonad, I get this error: Not in scope: 'W.shift' am I missing an import or something? thanks -matt