    -----------------------------------------------------------------------------
    -- |
    -- Module      :  XMonad.Actions.DwmPromote
    -- Description :  DWM-like swap function for xmonad.
    -- Copyright   :  (c) Miikka Koskinen 2007
    -- License     :  BSD3-style (see LICENSE)
    --
    -- Maintainer  :  arcatan@kapsi.fi
    -- Stability   :  stable
    -- Portability :  unportable
    --
    -- Dwm-like swap function for xmonad.
    --
    -- Swaps focused window with the master window. If focus is in the
    -- master, swap it with the next window in the stack. Focus stays in the
    -- master.
    --
    -----------------------------------------------------------------------------

    module XMonad.Actions.DwmPromote (
                                     -- * Usage
                                     -- $usage
                                     dwmpromote
                                    ) where

    import XMonad
    import XMonad.StackSet
    import XMonad.Prelude

    import qualified Data.List.NonEmpty as NE

    -- $usage
    --
    -- You can use this module with the following in your @xmonad.hs@:
    --
    -- >    import XMonad.Actions.DwmPromote
    --
    -- then add a keybinding or substitute 'dwmpromote' in place of promote:
    --
    -- >   , ((modm,               xK_Return), dwmpromote)
    --
    -- For detailed instructions on editing your key bindings, see
    -- <https://xmonad.org/TUTORIAL.html#customizing-xmonad the tutorial>.

    -- | Swap the focused window with the master window. If focus is in
    --   the master, swap it with the next window in the stack. Focus
    --   stays in the master.
    dwmpromote :: X ()
    dwmpromote :: X ()
    dwmpromote = (WindowSet -> WindowSet) -> X ()
    windows ((WindowSet -> WindowSet) -> X ())
    -> (WindowSet -> WindowSet) -> X ()
    forall a b. (a -> b) -> a -> b
    $ (Stack Window -> Stack Window) -> WindowSet -> WindowSet
    forall a i l s sd.
    (Stack a -> Stack a) -> StackSet i l a s sd -> StackSet i l a s sd
    modify' ((Stack Window -> Stack Window) -> WindowSet -> WindowSet)
    -> (Stack Window -> Stack Window) -> WindowSet -> WindowSet
    forall a b. (a -> b) -> a -> b
    $
                 \Stack Window
    c -> case Stack Window
    c of
                       Stack Window
    _ []     []     -> Stack Window
    c
                       Stack Window
    t []     (Window
    r:[Window]
    rs) -> Window -> [Window] -> [Window] -> Stack Window
    forall a. a -> [a] -> [a] -> Stack a
    Stack Window
    r [] (Window
    tWindow -> [Window] -> [Window]
    forall a. a -> [a] -> [a]
    :[Window]
    rs)
                       Stack Window
    t (Window
    l:[Window]
    ls) [Window]
    rs     -> Window -> [Window] -> [Window] -> Stack Window
    forall a. a -> [a] -> [a] -> Stack a
    Stack Window
    t [] ([Window]
    ys [Window] -> [Window] -> [Window]
    forall a. [a] -> [a] -> [a]
    ++ Window
    y Window -> [Window] -> [Window]
    forall a. a -> [a] -> [a]
    : [Window]
    rs) where (Window
    y :| [Window]
    ys) = NonEmpty Window -> NonEmpty Window
    forall a. NonEmpty a -> NonEmpty a
    NE.reverse (Window
    l Window -> [Window] -> NonEmpty Window
    forall a. a -> [a] -> NonEmpty a
    :| [Window]
    ls)