xmonad.hs

inputMode :: [( (KeyMask, KeySym), (X () ) )] -> X ()
inputMode xs = do
    submap . M.fromList $ modeMap where
        modeMap = [ ( ( km, ks ), do x
                                     (submap . M.fromList $ modeMap) )
                    | ( ( km, ks ), x ) <- xs
                  ] ++ [((0, xK_Escape), return ())]


moveMode =
    [ ((0, xK_h), withFocused (keysMoveWindow (-15,0) ) )
    , ((0, xK_l), withFocused (keysMoveWindow (15,0) ) )
    , ((0, xK_k), withFocused (keysMoveWindow (0,-15) ) )
    , ((0, xK_j), withFocused (keysMoveWindow (0,15) ) )
    , ((controlMask, xK_h), withFocused (keysMoveWindow (-1,0) ) )
    , ((controlMask, xK_l), withFocused (keysMoveWindow (1,0) ) )
    , ((controlMask, xK_k), withFocused (keysMoveWindow (0,-1) ) )
    , ((controlMask, xK_j), withFocused (keysMoveWindow (0,1) ) )
    , ((0,         xK_Tab), focusDown )
    ]

myKeys conf@(XConfig {XMonad.modMask = modm}) = M.fromList $
    [ ...
    -- floating: move and resize with h, j, k, l. These are modes. Just hit modm+g and then
    -- use plain h,j,k,l. Hit Esc when done
    , ((modm,                 xK_g), inputMode moveMode)
    ...
    ]

Here's a version that cuts down on some of the code duplication

moveMode = submap . M.fromList $
    [ ((m, k), do withFocused (keysMoveWindow (c*dx, c*dy))
                  moveMode)
      | let big   = 15
            small = 1
      , (k,dx,dy) <- [ (xK_h, -1,  0)
                     , (xK_l,  1,  0)
                     , (xK_k,  0, -1)
                     , (xK_j,  0,  1)
                     ]
      , (c, m) <- [(big, 0), (small, controlMask)]
    ]

@byorgey: I totally re wrote the thing to make it a function. BTW your tip is still useful to generate the movMode mapping.