diff options
Diffstat (limited to 'XMonad')
| -rw-r--r-- | XMonad/Layout/LayoutBuilderP.hs | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/XMonad/Layout/LayoutBuilderP.hs b/XMonad/Layout/LayoutBuilderP.hs index 6ff48d0..aee6c6a 100644 --- a/XMonad/Layout/LayoutBuilderP.hs +++ b/XMonad/Layout/LayoutBuilderP.hs @@ -20,7 +20,7 @@ module XMonad.Layout.LayoutBuilderP ( B.relBox, B.absBox, -- * Overloading ways to select windows -- $selectWin - Predicate (..), + Predicate (..), Proxy(..), ) where import Control.Monad @@ -42,13 +42,16 @@ import qualified XMonad.Layout.LayoutBuilder as B -- | Type class for predicates. This enables us to manage not only Windows, -- but any objects, for which instance Predicate is defined. --- We assume that for all w checkPredicate (alwaysTrue undefined) == return True. -- -- Another instance exists in XMonad.Util.WindowPropertiesRE in xmonad-extras class Predicate p w where - alwaysTrue :: w -> p -- ^ A predicate that is always True. First argument is dummy, we always set it to undefined + alwaysTrue :: Proxy w -> p -- ^ A predicate that is always True. checkPredicate :: p -> w -> X Bool -- ^ Check if given object (window or smth else) matches that predicate +-- | Contains no actual data, but is needed to help select the correct instance +-- of 'Predicate' +data Proxy a = Proxy + -- | Data type for our layout. data LayoutP p l1 l2 a = LayoutP (Maybe a) (Maybe a) p B.SubBox (Maybe B.SubBox) (l1 a) (Maybe (l2 a)) @@ -71,7 +74,7 @@ layoutAll :: forall l1 p a. (Read a, Eq a, LayoutClass l1 a, Predicate p a) => -> l1 a -- ^ The layout to use in the specified area -> LayoutP p l1 Full a -- ^ The resulting layout layoutAll box sub = - let a = alwaysTrue (undefined :: a) + let a = alwaysTrue (Proxy :: Proxy a) in LayoutP Nothing Nothing a box Nothing sub Nothing instance (LayoutClass l1 w, LayoutClass l2 w, Predicate p w, Show w, Read w, Eq w, Typeable w, Show p) => |