mirror of
https://github.com/xmonad/xmonad-contrib.git
synced 2025-07-31 20:21:51 -07:00
49 lines
1.4 KiB
Haskell
49 lines
1.4 KiB
Haskell
-----------------------------------------------------------------------------
|
|
-- |
|
|
-- Module : XMonadContrib.Invisible
|
|
-- Copyright : (c) 2007 Andrea Rossato, David Roundy
|
|
-- License : BSD-style (see xmonad/LICENSE)
|
|
--
|
|
-- Maintainer : andrea.rossato@unibz.it, droundy@darcs.net
|
|
-- Stability : unstable
|
|
-- Portability : unportable
|
|
--
|
|
-- A data type to store the layout state
|
|
--
|
|
-----------------------------------------------------------------------------
|
|
|
|
module XMonadContrib.Invisible (
|
|
-- * Usage:
|
|
-- $usage
|
|
Invisible (..)
|
|
, whenIJust
|
|
, fromIMaybe
|
|
) where
|
|
|
|
-- $usage
|
|
-- A data type to store the layout state
|
|
|
|
data Invisible m a = I (m a)
|
|
|
|
instance (Functor m, Monad m) => Read (Invisible m a) where
|
|
readsPrec _ s = [(fail "Read Invisible", s)]
|
|
|
|
instance Monad m => Show (Invisible m a) where
|
|
show _ = ""
|
|
|
|
instance (Functor m, Monad m) => Monad (Invisible m) where
|
|
return a = I (return a)
|
|
m >>= f = m >>= f
|
|
fail s = I (fail s)
|
|
|
|
instance (Functor m, Monad m) => Functor (Invisible m) where
|
|
fmap f (I x) = I (fmap f x)
|
|
|
|
whenIJust :: (Monad m) => Invisible Maybe a -> (a -> m ()) -> m ()
|
|
whenIJust (I (Just x)) f = f x
|
|
whenIJust (I Nothing) _ = return ()
|
|
|
|
fromIMaybe :: a -> Invisible Maybe a -> a
|
|
fromIMaybe _ (I (Just x)) = x
|
|
fromIMaybe a (I Nothing) = a
|