David, Spencer et al, are there any problems with restricting layoutMsg
arguments to being members of the (open) Message class? I'd (strongly)
prefer this over just Dynamic, since it restores most of the static
checking we'd need.
The only change for something like Mosaic would be to add the mosaic
events to Message, with instance Message MyType, and to switch layoutMsg
to sendMessage (its our 'throw' for dynamically extensible messages, in
fact).
The idea of constrained extensible messages is from SimonM's 06 HW paper
on extensible exceptions.
Comments?
-- Don
New patches:
[Constrain layout messages to be members of a Message class
Don Stewart **20070504075233
Using Typeables as the only constraint on layout messages is a bit
scary, as a user can send arbitrary values to layoutMsg, whether they
make sense or not: there's basically no type feedback on the values you
supply to layoutMsg.
Folloing Simon Marlow's dynamically extensible exceptions paper, we use
an existential type, and a Message type class, to constrain valid
arguments to layoutMsg to be valid members of Message.
That is, a user writes some data type for messages their layout
algorithm accepts:
data MyLayoutEvent = Zoom
| Explode
| Flaming3DGlassEffect
deriving (Typeable)
and they then add this to the set of valid message types:
instance Message MyLayoutEvent
Done. We also reimplement the dynamic type check while we're here, to
just directly use 'cast', rather than expose a raw fromDynamic/toDyn.
With this, I'm much happier about out dynamically extensible layout
event subsystem.
] {
hunk ./Config.hs 157
- , ((modMask, xK_h ), layoutMsg Shrink)
- , ((modMask, xK_l ), layoutMsg Expand)
+ , ((modMask, xK_h ), sendMessage Shrink)
+ , ((modMask, xK_l ), sendMessage Expand)
hunk ./Operations.hs 19
-import Data.Dynamic ( Typeable, toDyn, fromDynamic )
hunk ./Operations.hs 77
+-- | Throw an (extensible) message value to the current Layout scheme,
+-- possibly modifying how we layout the windows, then refresh.
hunk ./Operations.hs 80
--- TODO, using Typeable for extensible stuff is a bit gunky. Check --
--- 'extensible exceptions' paper for other ideas.
+-- TODO, this will refresh on Nothing.
hunk ./Operations.hs 82
--- Basically this thing specifies the basic operations that vary between
--- layouts.
---
-data ShrinkOrExpand = Shrink | Expand deriving (Typeable, Eq)
-
-layoutMsg :: Typeable a => a -> X () -- FIXME: The below shouldn't refresh on Nothing
-layoutMsg a = layout $ \x@(l:ls) -> maybe x (:ls) (modifyLayout l (toDyn a))
+sendMessage :: Message a => a -> X ()
+sendMessage m = layout $ \xs -> case xs of
+ [] -> []
+ (l:ls) -> maybe xs (:ls) $ modifyLayout l (SomeMessage m)
hunk ./Operations.hs 87
+------------------------------------------------------------------------
hunk ./Operations.hs 89
--- Standard layout algorithms:
+-- Builtin layout algorithms:
hunk ./Operations.hs 94
+--
+-- The latter algorithms support the following operations:
hunk ./Operations.hs 97
-full :: Layout
-tall, wide :: Rational -> Rational -> Layout
+-- Shrink
+-- Expand
+--
+
+data Resize = Shrink | Expand deriving (Typeable, Show)
+instance Message Resize
hunk ./Operations.hs 104
-full = Layout { doLayout = \sc ws -> [ (w,sc) | w <- ws ]
- , modifyLayout = const Nothing }
+full :: Layout
+full = Layout { doLayout = \sc ws -> [ (w,sc) | w <- ws ]
+ , modifyLayout = const Nothing } -- no changes
hunk ./Operations.hs 108
+tall, wide :: Rational -> Rational -> Layout
hunk ./Operations.hs 112
- , modifyLayout = fmap f . fromDynamic }
+ , modifyLayout = fmap handler . fromMessage }
hunk ./Operations.hs 114
- where f s = tall delta ((op s) frac delta)
- op Shrink = (-) ; op Expand = (+)
+ where handler s = tall delta $ (case s of
+ Shrink -> (-)
+ Expand -> (+)) frac delta
hunk ./XMonad.hs 20
+ Typeable, Message, SomeMessage(..), fromMessage,
hunk ./XMonad.hs 32
-import Data.Dynamic ( Dynamic )
+import Data.Typeable
hunk ./XMonad.hs 40
- , layouts :: !(M.Map WorkspaceId [Layout]) -- ^ mapping of workspaces
+ , layouts :: !(M.Map WorkspaceId [Layout]) } -- ^ mapping of workspaces
hunk ./XMonad.hs 42
- }
hunk ./XMonad.hs 54
- , focusedBorder :: !Color -- ^ border color of the focused window
- }
+ , focusedBorder :: !Color } -- ^ border color of the focused window
hunk ./XMonad.hs 96
--- 'doLayout', a pure function to layout a Window set
--- 'modifyLayout',
+-- 'doLayout', a pure function to layout a Window set 'modifyLayout',
+-- 'modifyLayout' can be considered a branch of an exception handler.
+--
hunk ./XMonad.hs 100
- , modifyLayout :: Dynamic -> Maybe Layout }
+ , modifyLayout :: SomeMessage -> Maybe Layout }
+
+-- Based on ideas in /An Extensible Dynamically-Typed Hierarchy of Exceptions/,
+-- Simon Marlow, 2006. Use extensible messages to the modifyLayout handler.
+--
+-- User-extensible messages must be a member of this class:
+--
+class (Typeable a, Show a) => Message a
+
+--
+-- A wrapped value of some type in the Message class.
+--
+data SomeMessage = forall a. Message a => SomeMessage a
+
+--
+-- And now, unwrap a given, unknown Message type, performing a (dynamic)
+-- type check on the result.
+--
+fromMessage :: Message m => SomeMessage -> Maybe m
+fromMessage (SomeMessage m) = cast m
}
Context:
[refactoring, style, comments on new layout code
Don Stewart **20070504023618]
[use anyKey constant instead of magic number
Jason Creighton **20070504015043]
[added mirrorLayout to mirror arbitrary layouts
Jason Creighton **20070504014653]
[Fix layout switching order
Spencer Janssen **20070503235632]
[More Config.hs bugs
Spencer Janssen **20070503234607]
[Revert accidental change to Config.hs
Spencer Janssen **20070503233148]
[Add -fglasgow-exts for pattern guards. Properties.hs doesn't complain anymore
Spencer Janssen **20070503214221]
[Avoid the unsafe pattern match, in case Config.hs has no layouts
Spencer Janssen **20070503214007]
[add support for extensible layouts.
David Roundy **20070503144750]
[comments. and stop tracing events to stderr
Don Stewart **20070503075821]
[-Wall police
Don Stewart **20070503074937]
[elaborate documentation in Config.hs
Don Stewart **20070503074843]
[Use updated refreshKeyboardMapping. Requires latest X11-extras
Spencer Janssen **20070503032040]
[run QC tests in addition to LOC test
Jason Creighton **20070503003202]
[Add 'mod-n': refreshes current layout
Spencer Janssen **20070503002252]
[Fix tests after StackSet changes
Spencer Janssen **20070502201622]
[First steps to adding floating layer
Spencer Janssen **20070502195917]
[update motivational text using xmonad.org
Don Stewart **20070502061859]
[Sort dependencies in installation order
Spencer Janssen **20070501204249]
[Recommend X11-extras 0.1
Spencer Janssen **20070501204121]
[elaborate description in .cabal
Don Stewart **20070501035414]
[use -fasm by default. Much faster
Don Stewart **20070501031220]
[Make border width configurable
Spencer Janssen **20070430163515]
[Add Config.hs-boot, remove defaultLayoutDesc from XConf
Spencer Janssen **20070430162647]
[Comment only
Spencer Janssen **20070430161635]
[Comment only
Spencer Janssen **20070430161511]
[check we never generate invalid stack sets
Don Stewart **20070430065946]
[view n . shift n . view i . shift i) x == x --> shift + view is invertible
Don Stewart **20070430062901]
[add rotate all and view idempotency tests
Don Stewart **20070430055751]
[Add XConf for values that don't change.
Spencer Janssen **20070430054715]
[Control.Arrow is suspicious, add an explicit import
Spencer Janssen **20070430053623]
[push is idempotent
Don Stewart **20070430054345]
[add two properties relating to empty window managers
Don Stewart **20070430051016]
[configurable border colors
Jason Creighton **20070430043859
This also fixes a bug where xmonad was assuming a 24-bit display, and just
using, eg, 0xff0000 as an index into a colormap without querying the X server
to determine the proper pixel value for "red".
]
[new QC property: opening a window only affects the current screen
Don Stewart **20070430050133]
[a bit more precise about building non-empty stacksets for one test
Don Stewart **20070430035729]
[remove redundant call to 'delete' in 'shift'
Don Stewart **20070430031151]
[clean 'delete' a little
Don Stewart **20070430025319]
[shrink 'swap'
Don Stewart **20070430024813]
[shrink 'rotate' a little
Don Stewart **20070430024525]
[move size into Properties.hs
Don Stewart **20070430021758]
[don't need 'size' operation on StackSet
Don Stewart **20070430015927]
[avoid grabbing all keys when a keysym is undefined
Jason Creighton **20070428180046
XKeysymToKeycode() returns zero if the keysym is undefined. Zero also happens
to be the value of AnyKey.
]
[add homepage: field to .cabal file
Don Stewart **20070429041011]
[add fromList to Properties.hs
Don Stewart **20070429035823]
[move fromList into Properties.hs, -17 loc
Don Stewart **20070429035804]
[Further refactoring
Spencer Janssen **20070426212257]
[Refactor in Config.hs (no real changes)
Spencer Janssen **20070426211407]
[Add the manpage to extra-source-files
Spencer Janssen **20070426014105]
[add xmonad manpage
David Lazar **20070426010812]
[Remove toList
Spencer Janssen **20070426005713]
[Ignore numlock and capslock in keybindings
Jason Creighton **20070424013357]
[Clear numlock bit
Spencer Janssen **20070424010352]
[force window border to 1px
Jason Creighton **20070423050824]
[s/creigh//
Don Stewart **20070423024026]
[some other things to do
Don Stewart **20070423023151]
[Start TODOs for 0.2
Spencer Janssen **20070423021526]
[update readme
Don Stewart **20070422090507]
[TAG 0.1
Spencer Janssen **20070422083033]
Patch bundle hash:
58f3c7c9b1d98e93c2a0aa388fd91f7ee5567446
