[xmonad] Fwd: Patch to add new Layout message

[Mike Meyer]

That works. I didn't try it directly, but cleaned it up a little
Damn it, you tricked me into writing it:

{-# LANGUAGE DeriveDataTypeable, FlexibleInstances, MultiParamTypeClasses
#-}

import Control.Arrow
import XMonad
import XMonad.StackSet

data Flippy a = Flippy (Tall a) deriving (Show, Read)
data Flip = Flip deriving Typeable
instance Message Flip

instance LayoutClass Flippy a where
    runLayout (Workspace id (Flippy tall) ms) r =
      fmap (second (fmap Flippy)) $ runLayout (Workspace id tall ms) r

    handleMessage (Flippy tall) m =
      case flip of
        Just _  -> return $ doFlip (Flippy tall)
        Nothing -> fmap (fmap Flippy) $ handleMessage tall m
      where flip = fromMessage m :: Maybe Flip
            doFlip (Flippy (Tall 1 delta frac)) = Just $ Flippy $ Tall 2
delta frac
            doFlip (Flippy (Tall _ delta frac)) = Just $ Flippy $ Tall 1
delta frac

    description _ = "Flippy"

No guarantee this works, but it compiles.

On Wed, Oct 1, 2014 at 6:10 PM, Brandon Allbery <allbery.b at gmail.com> wrote:

> On Wed, Oct 1, 2014 at 7:03 PM, Devin Mullins <devin.mullins at gmail.com>
> wrote:
>
>> I think another option is to make a new instance of LayoutClass that is
>> just like Tall except for also supporting this message. In fact, you should
>> be able to delegate to Tall for most definitions. Just writing off the cuff
>> - could be wrong.
>>
>
> Delegating to Tall won't work; you'd have to copy the definition and
> modify it, like I suggested for (|||).
>
> --
> brandon s allbery kf8nh                               sine nomine
> associates
> allbery.b at gmail.com
> ballbery at sinenomine.net
> unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
>
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