@@ -4,69 +4,18 @@ Description: Basic set of widgets and building blocks for reflex-vty application
5{-# Language UndecidableInstances #-}
5{-# Language UndecidableInstances #-}
7−module Reflex.Vty.Widget
7+module Reflex.Vty.Widget where
14− , mainWidgetWithHandle
18− , HasVtyWidgetCtx(..)
28− , ScrollDirection(..)
58import Control.Applicative (liftA2)
9import Control.Applicative (liftA2)
59import Control.Monad.Fix (MonadFix)
10import Control.Monad.Fix (MonadFix)
60import Control.Monad.IO.Class (MonadIO)
11import Control.Monad.IO.Class (MonadIO)
12+import Control.Monad.Morph
61import Control.Monad.NodeId
13import Control.Monad.NodeId
62−import Control.Monad.Reader (ReaderT, ask, asks, local, runReaderT)
14+import Control.Monad.Reader (ReaderT, ask, local, runReaderT)
15+import Control.Monad.Ref
63import Control.Monad.Trans (MonadTrans, lift)
16import Control.Monad.Trans (MonadTrans, lift)
64−import Data.Default (Default(..))
65import Data.Set (Set)
17import Data.Set (Set)
66import qualified Data.Set as Set
18import qualified Data.Set as Set
67−import Data.Text (Text)
68−import qualified Data.Text as T
69−import qualified Data.Text.Zipper as TZ
70import Graphics.Vty (Image)
19import Graphics.Vty (Image)
71import qualified Graphics.Vty as V
20import qualified Graphics.Vty as V
72import Reflex
21import Reflex
@@ -74,88 +23,20 @@ import Reflex.Class ()
74import Reflex.Host.Class (MonadReflexCreateTrigger)
23import Reflex.Host.Class (MonadReflexCreateTrigger)
75import Reflex.Vty.Host
24import Reflex.Vty.Host
77−-- | The context within which a 'VtyWidget' runs
26+-- * Running a vty application
78−data VtyWidgetCtx t = VtyWidgetCtx
79− { _vtyWidgetCtx_width :: Dynamic t Int
80− -- ^ The width of the region allocated to the widget.
81− , _vtyWidgetCtx_height :: Dynamic t Int
82− -- ^ The height of the region allocated to the widget.
83− , _vtyWidgetCtx_focus :: Dynamic t Bool
84− -- ^ Whether the widget should behave as if it has focus for keyboard input.
85− , _vtyWidgetCtx_input :: Event t VtyEvent
86− -- ^ User input events that the widget's parent chooses to share. These will generally
87− -- be filtered for relevance:
88− -- * Keyboard inputs are restricted to focused widgets
89− -- * Mouse inputs are restricted to the region in which the widget resides and are
90− -- translated into its internal coordinates.
93−-- | The output of a 'VtyWidget'
94−data VtyWidgetOut t = VtyWidgetOut
95− { _vtyWidgetOut_shutdown :: Event t ()
98−instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (VtyWidget t m) where
99− runWithReplace a0 a' = VtyWidget $ runWithReplace (unVtyWidget a0) $ fmap unVtyWidget a'
100− traverseIntMapWithKeyWithAdjust f dm0 dm' = VtyWidget $
101− traverseIntMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
102− traverseDMapWithKeyWithAdjust f dm0 dm' = VtyWidget $ do
103− traverseDMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
104− traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = VtyWidget $ do
105− traverseDMapWithKeyWithAdjustWithMove (\k v -> unVtyWidget (f k v)) dm0 dm'
107−-- | A widget that can read its context and produce image output
108−newtype VtyWidget t m a = VtyWidget
109− { unVtyWidget :: BehaviorWriterT t [Image] (ReaderT (VtyWidgetCtx t) m) a
121− , MonadReflexCreateTrigger t
125−deriving instance PerformEvent t m => PerformEvent t (VtyWidget t m)
126−instance MonadTrans (VtyWidget t) where
127− lift f = VtyWidget $ lift $ lift f
129−instance MonadNodeId m => MonadNodeId (VtyWidget t m) where
130− getNextNodeId = VtyWidget $ do
131− lift $ lift getNextNodeId
133−-- | A reader-like class for the vty widget context. Allows actions to be run in a sub-context.
134−class HasVtyWidgetCtx t m | m -> t where
135− askCtx :: m (VtyWidgetCtx t)
136− default askCtx :: (f m' ~ m, Monad m', MonadTrans f, HasVtyWidgetCtx t m') => m (VtyWidgetCtx t)
137− askCtx = lift askCtx
138− localCtx :: (VtyWidgetCtx t -> VtyWidgetCtx t) -> (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
140−instance (Monad m, Reflex t) => HasVtyWidgetCtx t (VtyWidget t m) where
141− askCtx = VtyWidget $ lift ask
142− localCtx f g (VtyWidget x) = VtyWidget $ do
143− (a, images) :: (a, Behavior t [Image]) <- lift $ local f $ runBehaviorWriterT x
144− tellImages $ g images
147−-- | Runs a 'VtyWidget' with a given context
149− :: (Reflex t, MonadNodeId m)
152− -> m (a, Behavior t [Image])
153−runVtyWidget ctx w = runReaderT (runBehaviorWriterT (unVtyWidget w)) ctx
155−-- | Sets up the top-level context for a 'VtyWidget' and runs it with that context
28+-- | Sets up the top-level context for a vty widget and runs it with that context
156mainWidgetWithHandle
29mainWidgetWithHandle
158− -> (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
32+ ( MonadVtyApp t m
35+ , HasDisplayRegion t m
160mainWidgetWithHandle vty child =
41mainWidgetWithHandle vty child =
161 runVtyAppWithHandle vty $ \dr0 inp -> do
42 runVtyAppWithHandle vty $ \dr0 inp -> do
@@ -165,77 +46,178 @@ mainWidgetWithHandle vty child =
165 let inp' = fforMaybe inp $ \case
46 let inp' = fforMaybe inp $ \case
166 V.EvResize {} -> Nothing
47 V.EvResize {} -> Nothing
167 x -> Just x
48 x -> Just x
168− let ctx = VtyWidgetCtx
49+ (shutdown, images) <- runThemeReader (constant V.defAttr) $
169− { _vtyWidgetCtx_width = fmap fst size
50+ runFocusReader (pure True) $
170− , _vtyWidgetCtx_height = fmap snd size
51+ runDisplayRegion (fmap (\(w, h) -> Region 0 0 w h) size) $
171− , _vtyWidgetCtx_input = inp'
52+ runImageWriter $
172− , _vtyWidgetCtx_focus = constDyn True
53+ runNodeIdT $
173− }
54+ runInput inp' $ do
174− (shutdown, images) <- runNodeIdT $ runVtyWidget ctx $ do
175− tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
55+ tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
177 return $ VtyResult
57 return $ VtyResult
178 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
58 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
179 , _vtyResult_shutdown = shutdown
59 , _vtyResult_shutdown = shutdown
62+-- | The output of a vty widget
63+data VtyWidgetOut t = VtyWidgetOut
64+ { _vtyWidgetOut_shutdown :: Event t ()
182-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
67-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
183mainWidget
68mainWidget
184− :: (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
70+ ( MonadVtyApp t m
73+ , HasDisplayRegion t m
186mainWidget child = do
79mainWidget child = do
187 vty <- getDefaultVty
80 vty <- getDefaultVty
188 mainWidgetWithHandle vty child
81 mainWidgetWithHandle vty child
190−-- | A class for things that know their own display size dimensions
83+-- * Input Events
191−class (Reflex t, Monad m) => HasDisplaySize t m | m -> t where
192− -- | Retrieve the display width (columns)
193− displayWidth :: m (Dynamic t Int)
194− default displayWidth :: (f m' ~ m, MonadTrans f, HasDisplaySize t m') => m (Dynamic t Int)
195− displayWidth = lift displayWidth
196− -- | Retrieve the display height (rows)
197− displayHeight :: m (Dynamic t Int)
198− default displayHeight :: (f m' ~ m, MonadTrans f, HasDisplaySize t m') => m (Dynamic t Int)
199− displayHeight = lift displayHeight
201−instance (Reflex t, Monad m) => HasDisplaySize t (VtyWidget t m) where
202− displayWidth = VtyWidget . lift $ asks _vtyWidgetCtx_width
203− displayHeight = VtyWidget . lift $ asks _vtyWidgetCtx_height
205−instance HasDisplaySize t m => HasDisplaySize t (ReaderT x m)
206−instance HasDisplaySize t m => HasDisplaySize t (BehaviorWriterT t x m)
207−instance HasDisplaySize t m => HasDisplaySize t (DynamicWriterT t x m)
208−instance HasDisplaySize t m => HasDisplaySize t (EventWriterT t x m)
210−instance HasDisplaySize t m => HasDisplaySize t (NodeIdT m)
212-- | A class for things that can receive vty events as input
85-- | A class for things that can receive vty events as input
213−class HasVtyInput t m | m -> t where
86+class HasInput t m | m -> t where
214 input :: m (Event t VtyEvent)
87 input :: m (Event t VtyEvent)
215− default input :: (f m' ~ m, Monad m', MonadTrans f, HasVtyInput t m') => m (Event t VtyEvent)
88+ default input :: (f m' ~ m, Monad m', MonadTrans f, HasInput t m') => m (Event t VtyEvent)
216 input = lift input
89 input = lift input
90+ -- | User input events that the widget's parent chooses to share. These will generally
91+ -- be filtered for relevance.
92+ localInput :: (Event t VtyEvent -> Event t VtyEvent) -> m a -> m a
93+ default localInput :: (f m' ~ m, Monad m', MFunctor f, HasInput t m') => (Event t VtyEvent -> Event t VtyEvent) -> m a -> m a
94+ localInput f = hoist (localInput f)
96+instance (Reflex t, Monad m) => HasInput t (Input t m) where
98+ localInput f (Input m) = Input $ local f m
100+-- | A widget that can receive input events. See 'Graphics.Vty.Event'
101+newtype Input t m a = Input
102+ { unInput :: ReaderT (Event t VtyEvent) m a
218−instance (Reflex t, Monad m) => HasVtyInput t (VtyWidget t m) where
114+instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (Input t m) where
219− input = VtyWidget . lift $ asks _vtyWidgetCtx_input
115+ runWithReplace a0 a' = Input $ runWithReplace (unInput a0) $ fmap unInput a'
116+ traverseIntMapWithKeyWithAdjust f dm0 dm' = Input $
117+ traverseIntMapWithKeyWithAdjust (\k v -> unInput (f k v)) dm0 dm'
118+ traverseDMapWithKeyWithAdjust f dm0 dm' = Input $ do
119+ traverseDMapWithKeyWithAdjust (\k v -> unInput (f k v)) dm0 dm'
120+ traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = Input $ do
121+ traverseDMapWithKeyWithAdjustWithMove (\k v -> unInput (f k v)) dm0 dm'
123+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (Input t m)
124+deriving instance NotReady t m => NotReady t (Input t m)
125+deriving instance PerformEvent t m => PerformEvent t (Input t m)
126+deriving instance PostBuild t m => PostBuild t (Input t m)
127+deriving instance TriggerEvent t m => TriggerEvent t (Input t m)
128+instance HasImageWriter t m => HasImageWriter t (Input t m)
129+instance HasDisplayRegion t m => HasDisplayRegion t (Input t m)
130+instance HasFocusReader t m => HasFocusReader t (Input t m)
132+instance MonadTrans (Input t) where
133+ lift f = Input $ lift f
135+instance MFunctor (Input t) where
136+ hoist f = Input . hoist f . unInput
138+instance MonadNodeId m => MonadNodeId (Input t m)
140+-- | Runs an 'Input' with a given context
146+runInput e w = runReaderT (unInput w) e
221−-- | A class for things that can dynamically gain and lose focus
148+-- ** Filtering input
222−class HasFocus t m | m -> t where
223− focus :: m (Dynamic t Bool)
224− default focus :: (f m' ~ m, Monad m', MonadTrans f, HasFocus t m') => m (Dynamic t Bool)
227−instance (Reflex t, Monad m) => HasFocus t (VtyWidget t m) where
150+-- | Type synonym for a key and modifier combination
228− focus = VtyWidget . lift $ asks _vtyWidgetCtx_focus
151+type KeyCombo = (V.Key, [V.Modifier])
230−-- | A class for widgets that can produce images to draw to the display
153+-- | Emits an event that fires on a particular key press (without modifiers)
154+key :: (Monad m, Reflex t, HasInput t m) => V.Key -> m (Event t KeyCombo)
155+key = keyCombos . Set.singleton . (,[])
157+-- | Emits an event that fires on particular key presses (without modifiers)
158+keys :: (Monad m, Reflex t, HasInput t m) => [V.Key] -> m (Event t KeyCombo)
159+keys = keyCombos . Set.fromList . fmap (,[])
161+-- | Emit an event that fires whenever the provided key combination occurs
231−class (Reflex t, Monad m) => ImageWriter t m | m -> t where
163+ :: (Reflex t, Monad m, HasInput t m)
232− -- | Send images upstream for rendering
164+ => KeyCombo
233− tellImages :: Behavior t [Image] -> m ()
165+ -> m (Event t KeyCombo)
234− default tellImages :: (f m' ~ m, Monad m', MonadTrans f, ImageWriter t m') => Behavior t [Image] -> m ()
166+keyCombo = keyCombos . Set.singleton
235− tellImages = lift . tellImages
237−instance (Monad m, Reflex t) => ImageWriter t (BehaviorWriterT t [Image] m) where
168+-- | Emit an event that fires whenever any of the provided key combinations occur
238− tellImages = tellBehavior
169+keyCombos
170+ :: (Reflex t, Monad m, HasInput t m)
172+ -> m (Event t KeyCombo)
175+ return $ fforMaybe i $ \case
176+ V.EvKey k m -> if Set.member (k, m) ks
181+-- | Filter the keyboard input that a child widget may receive
182+filterKeys :: (Reflex t, HasInput t m) => (KeyCombo -> Bool) -> m a -> m a
183+filterKeys f x = localInput (ffilter (\case
184+ V.EvKey k mods -> f (k, mods)
187+-- | Filter mouse input events based on whether they target a particular region
188+-- and translate them to the internal coordinate system of that region.
190+-- NB: Non-mouse events are passed through unfiltered and unchanged
191+mouseInRegion :: Region -> VtyEvent -> Maybe VtyEvent
192+mouseInRegion (Region l t w h) e = case e of
193+ V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
194+ V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
201+ , y >= t + h ] = Nothing
203+ Just (con (x - l) (y - t))
205+-- | Filter mouse input outside the current display region and
206+-- all input if the region is not focused
208+ :: (HasDisplayRegion t m, HasFocusReader t m, HasInput t m)
209+ => m (Event t VtyEvent)
210+inputInFocusedRegion = do
212+ reg <- current <$> askRegion
213+ foc <- current <$> focus
214+ pure $ fmapMaybe id $ attachWith filterInput ((,) <$> reg <*> foc) inp
216+ filterInput (r, f) = \case
217+ V.EvKey {} | not f -> Nothing
218+ x -> mouseInRegion r x
220+-- * Getting and setting the display region
240-- | A chunk of the display area
222-- | A chunk of the display area
241data Region = Region
223data Region = Region
@@ -246,14 +228,293 @@ data Region = Region
247 deriving (Show, Read, Eq, Ord)
229 deriving (Show, Read, Eq, Ord)
231+-- | A region that occupies no space.
233+nilRegion = Region 0 0 0 0
249-- | The width and height of a 'Region'
235-- | The width and height of a 'Region'
250regionSize :: Region -> (Int, Int)
236regionSize :: Region -> (Int, Int)
251regionSize (Region _ _ w h) = (w, h)
237regionSize (Region _ _ w h) = (w, h)
253-- | Produces an 'Image' that fills a region with space characters
239-- | Produces an 'Image' that fills a region with space characters
254−regionBlankImage :: Region -> Image
240+regionBlankImage :: V.Attr -> Region -> Image
255−regionBlankImage r@(Region _ _ width height) =
241+regionBlankImage attr r@(Region _ _ width height) =
256− withinImage r $ V.charFill V.defAttr ' ' width height
242+ withinImage r $ V.charFill attr ' ' width height
244+-- | A class for things that know their own display size dimensions
245+class (Reflex t, Monad m) => HasDisplayRegion t m | m -> t where
246+ -- | Retrieve the display region
247+ askRegion :: m (Dynamic t Region)
248+ default askRegion :: (f m' ~ m, MonadTrans f, HasDisplayRegion t m') => m (Dynamic t Region)
249+ askRegion = lift askRegion
250+ -- | Run an action in a local region, by applying a transformation to the region
251+ localRegion :: (Dynamic t Region -> Dynamic t Region) -> m a -> m a
252+ default localRegion :: (f m' ~ m, Monad m', MFunctor f, HasDisplayRegion t m') => (Dynamic t Region -> Dynamic t Region) -> m a -> m a
253+ localRegion f = hoist (localRegion f)
255+-- | Retrieve the display width
256+displayWidth :: HasDisplayRegion t m => m (Dynamic t Int)
257+displayWidth = fmap _region_width <$> askRegion
259+-- | Retrieve the display height
260+displayHeight :: HasDisplayRegion t m => m (Dynamic t Int)
261+displayHeight = fmap _region_height <$> askRegion
263+instance HasDisplayRegion t m => HasDisplayRegion t (ReaderT x m)
264+instance HasDisplayRegion t m => HasDisplayRegion t (BehaviorWriterT t x m)
265+instance HasDisplayRegion t m => HasDisplayRegion t (DynamicWriterT t x m)
266+instance HasDisplayRegion t m => HasDisplayRegion t (EventWriterT t x m)
267+instance HasDisplayRegion t m => HasDisplayRegion t (NodeIdT m)
269+-- | A widget that has access to a particular region of the vty display
270+newtype DisplayRegion t m a = DisplayRegion
271+ { unDisplayRegion :: ReaderT (Dynamic t Region) m a }
283+instance (Monad m, Reflex t) => HasDisplayRegion t (DisplayRegion t m) where
284+ askRegion = DisplayRegion ask
285+ localRegion f = DisplayRegion . local f . unDisplayRegion
287+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (DisplayRegion t m)
288+deriving instance NotReady t m => NotReady t (DisplayRegion t m)
289+deriving instance PerformEvent t m => PerformEvent t (DisplayRegion t m)
290+deriving instance PostBuild t m => PostBuild t (DisplayRegion t m)
291+deriving instance TriggerEvent t m => TriggerEvent t (DisplayRegion t m)
292+instance HasImageWriter t m => HasImageWriter t (DisplayRegion t m)
293+instance HasFocusReader t m => HasFocusReader t (DisplayRegion t m)
295+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (DisplayRegion t m) where
296+ runWithReplace (DisplayRegion a) e = DisplayRegion $ runWithReplace a $ fmap unDisplayRegion e
297+ traverseIntMapWithKeyWithAdjust f m e = DisplayRegion $ traverseIntMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
298+ traverseDMapWithKeyWithAdjust f m e = DisplayRegion $ traverseDMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
299+ traverseDMapWithKeyWithAdjustWithMove f m e = DisplayRegion $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unDisplayRegion $ f k v) m e
301+instance MonadTrans (DisplayRegion t) where
302+ lift = DisplayRegion . lift
304+instance MFunctor (DisplayRegion t) where
305+ hoist f = DisplayRegion . hoist f . unDisplayRegion
307+instance MonadNodeId m => MonadNodeId (DisplayRegion t m)
309+-- | Run a 'DisplayRegion' action with a given 'Region'
311+ :: (Reflex t, Monad m)
313+ -> DisplayRegion t m a
315+runDisplayRegion r = flip runReaderT r . unDisplayRegion
317+-- * Getting focus state
319+-- | A class for things that can dynamically gain and lose focus
320+class (Reflex t, Monad m) => HasFocusReader t m | m -> t where
321+ focus :: m (Dynamic t Bool)
322+ default focus :: (f m' ~ m, Monad m', MonadTrans f, HasFocusReader t m') => m (Dynamic t Bool)
324+ localFocus :: (Dynamic t Bool -> Dynamic t Bool) -> m a -> m a
325+ default localFocus :: (f m' ~ m, Monad m', MFunctor f, HasFocusReader t m') => (Dynamic t Bool -> Dynamic t Bool) -> m a -> m a
326+ localFocus f = hoist (localFocus f)
328+instance HasFocusReader t m => HasFocusReader t (ReaderT x m)
329+instance HasFocusReader t m => HasFocusReader t (BehaviorWriterT t x m)
330+instance HasFocusReader t m => HasFocusReader t (DynamicWriterT t x m)
331+instance HasFocusReader t m => HasFocusReader t (EventWriterT t x m)
332+instance HasFocusReader t m => HasFocusReader t (NodeIdT m)
334+-- | A widget that has access to information about whether it is focused
335+newtype FocusReader t m a = FocusReader
336+ { unFocusReader :: ReaderT (Dynamic t Bool) m a }
348+instance (Monad m, Reflex t) => HasFocusReader t (FocusReader t m) where
349+ focus = FocusReader ask
350+ localFocus f = FocusReader . local f . unFocusReader
352+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (FocusReader t m)
353+deriving instance NotReady t m => NotReady t (FocusReader t m)
354+deriving instance PerformEvent t m => PerformEvent t (FocusReader t m)
355+deriving instance PostBuild t m => PostBuild t (FocusReader t m)
356+deriving instance TriggerEvent t m => TriggerEvent t (FocusReader t m)
357+instance HasImageWriter t m => HasImageWriter t (FocusReader t m)
359+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (FocusReader t m) where
360+ runWithReplace (FocusReader a) e = FocusReader $ runWithReplace a $ fmap unFocusReader e
361+ traverseIntMapWithKeyWithAdjust f m e = FocusReader $ traverseIntMapWithKeyWithAdjust (\k v -> unFocusReader $ f k v) m e
362+ traverseDMapWithKeyWithAdjust f m e = FocusReader $ traverseDMapWithKeyWithAdjust (\k v -> unFocusReader $ f k v) m e
363+ traverseDMapWithKeyWithAdjustWithMove f m e = FocusReader $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unFocusReader $ f k v) m e
365+instance MonadTrans (FocusReader t) where
366+ lift = FocusReader . lift
368+instance MFunctor (FocusReader t) where
369+ hoist f = FocusReader . hoist f . unFocusReader
371+instance MonadNodeId m => MonadNodeId (FocusReader t m)
373+-- | Run a 'FocusReader' action with the given focus value
375+ :: (Reflex t, Monad m)
377+ -> FocusReader t m a
379+runFocusReader b = flip runReaderT b . unFocusReader
383+-- | A class for widgets that can produce images to draw to the display
384+class (Reflex t, Monad m) => HasImageWriter t m | m -> t where
385+ -- | Send images upstream for rendering
386+ tellImages :: Behavior t [Image] -> m ()
387+ default tellImages :: (f m' ~ m, Monad m', MonadTrans f, HasImageWriter t m') => Behavior t [Image] -> m ()
388+ tellImages = lift . tellImages
389+ -- | Apply a transformation to the images produced by the child actions
390+ mapImages :: (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
391+ default mapImages :: (f m' ~ m, Monad m', MFunctor f, HasImageWriter t m') => (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
392+ mapImages f = hoist (mapImages f)
394+-- | A widget that can produce images to draw onto the display
395+newtype ImageWriter t m a = ImageWriter
396+ { unImageWriter :: BehaviorWriterT t [Image] m a }
405+ , MonadReflexCreateTrigger t
413+instance MonadTrans (ImageWriter t) where
414+ lift = ImageWriter . lift
416+instance MFunctor (ImageWriter t) where
417+ hoist f = ImageWriter . (hoist f) . unImageWriter
419+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (ImageWriter t m) where
420+ runWithReplace (ImageWriter a) e = ImageWriter $ runWithReplace a $ fmap unImageWriter e
421+ traverseIntMapWithKeyWithAdjust f m e = ImageWriter $ traverseIntMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
422+ traverseDMapWithKeyWithAdjust f m e = ImageWriter $ traverseDMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
423+ traverseDMapWithKeyWithAdjustWithMove f m e = ImageWriter $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unImageWriter $ f k v) m e
425+instance HasImageWriter t m => HasImageWriter t (ReaderT x m)
426+instance HasImageWriter t m => HasImageWriter t (BehaviorWriterT t x m)
427+instance HasImageWriter t m => HasImageWriter t (DynamicWriterT t x m)
428+instance HasImageWriter t m => HasImageWriter t (EventWriterT t x m)
429+instance HasImageWriter t m => HasImageWriter t (NodeIdT m)
431+instance (Monad m, Reflex t) => HasImageWriter t (ImageWriter t m) where
432+ tellImages = ImageWriter . tellBehavior
433+ mapImages f (ImageWriter x) = ImageWriter $ do
434+ (a, images) <- lift $ runBehaviorWriterT x
435+ tellBehavior $ f images
438+instance HasDisplayRegion t m => HasDisplayRegion t (ImageWriter t m)
439+instance HasFocusReader t m => HasFocusReader t (ImageWriter t m)
441+-- | Run a widget that can produce images
443+ :: (Reflex t, Monad m)
444+ => ImageWriter t m a
445+ -> m (a, Behavior t [Image])
446+runImageWriter = runBehaviorWriterT . unImageWriter
450+-- | A class for things that can be visually styled
451+class (Reflex t, Monad m) => HasTheme t m | m -> t where
452+ theme :: m (Behavior t V.Attr)
453+ default theme :: (f m' ~ m, Monad m', MonadTrans f, HasTheme t m') => m (Behavior t V.Attr)
455+ localTheme :: (Behavior t V.Attr -> Behavior t V.Attr) -> m a -> m a
456+ default localTheme :: (f m' ~ m, Monad m', MFunctor f, HasTheme t m') => (Behavior t V.Attr -> Behavior t V.Attr) -> m a -> m a
457+ localTheme f = hoist (localTheme f)
459+instance HasTheme t m => HasTheme t (ReaderT x m)
460+instance HasTheme t m => HasTheme t (BehaviorWriterT t x m)
461+instance HasTheme t m => HasTheme t (DynamicWriterT t x m)
462+instance HasTheme t m => HasTheme t (EventWriterT t x m)
463+instance HasTheme t m => HasTheme t (NodeIdT m)
464+instance HasTheme t m => HasTheme t (Input t m)
465+instance HasTheme t m => HasTheme t (ImageWriter t m)
466+instance HasTheme t m => HasTheme t (DisplayRegion t m)
467+instance HasTheme t m => HasTheme t (FocusReader t m)
469+-- | A widget that has access to theme information
470+newtype ThemeReader t m a = ThemeReader
471+ { unThemeReader :: ReaderT (Behavior t V.Attr) m a }
483+instance (Monad m, Reflex t) => HasTheme t (ThemeReader t m) where
484+ theme = ThemeReader ask
485+ localTheme f = ThemeReader . local f . unThemeReader
487+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (ThemeReader t m)
488+deriving instance NotReady t m => NotReady t (ThemeReader t m)
489+deriving instance PerformEvent t m => PerformEvent t (ThemeReader t m)
490+deriving instance PostBuild t m => PostBuild t (ThemeReader t m)
491+deriving instance TriggerEvent t m => TriggerEvent t (ThemeReader t m)
492+instance HasImageWriter t m => HasImageWriter t (ThemeReader t m)
494+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (ThemeReader t m) where
495+ runWithReplace (ThemeReader a) e = ThemeReader $ runWithReplace a $ fmap unThemeReader e
496+ traverseIntMapWithKeyWithAdjust f m e = ThemeReader $ traverseIntMapWithKeyWithAdjust (\k v -> unThemeReader $ f k v) m e
497+ traverseDMapWithKeyWithAdjust f m e = ThemeReader $ traverseDMapWithKeyWithAdjust (\k v -> unThemeReader $ f k v) m e
498+ traverseDMapWithKeyWithAdjustWithMove f m e = ThemeReader $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unThemeReader $ f k v) m e
500+instance MonadTrans (ThemeReader t) where
501+ lift = ThemeReader . lift
503+instance MFunctor (ThemeReader t) where
504+ hoist f = ThemeReader . hoist f . unThemeReader
506+instance MonadNodeId m => MonadNodeId (ThemeReader t m)
508+-- | Run a 'ThemeReader' action with the given focus value
510+ :: (Reflex t, Monad m)
511+ => Behavior t V.Attr
512+ -> ThemeReader t m a
514+runThemeReader b = flip runReaderT b . unThemeReader
517+-- ** Manipulating images
258-- | Translates and crops an 'Image' so that it is contained by
519-- | Translates and crops an 'Image' so that it is contained by
259-- the given 'Region'.
520-- the given 'Region'.
@@ -265,7 +526,17 @@ withinImage (Region left top width height)
265 | width < 0 || height < 0 = withinImage (Region left top 0 0)
526 | width < 0 || height < 0 = withinImage (Region left top 0 0)
266 | otherwise = V.translate left top . V.crop width height
527 | otherwise = V.translate left top . V.crop width height
529+-- | Crop a behavior of images to a behavior of regions. See 'withinImage'.
532+ => Behavior t Region
533+ -> Behavior t [Image]
534+ -> Behavior t [Image]
535+imagesInRegion reg = liftA2 (\r is -> map (withinImage r) is) reg
537+-- * Running sub-widgets
268−-- | Low-level widget combinator that runs a child 'VtyWidget' within
539+-- | Low-level widget combinator that runs a child widget within
269-- a given region and context. This widget filters and modifies the input
540-- a given region and context. This widget filters and modifies the input
270-- that the child widget receives such that:
541-- that the child widget receives such that:
271-- * unfocused widgets receive no key events
542-- * unfocused widgets receive no key events
@@ -273,434 +544,17 @@ withinImage (Region left top width height)
273-- * mouse inputs inside the region have their coordinates translated such
544-- * mouse inputs inside the region have their coordinates translated such
274-- that (0,0) is the top-left corner of the region
545-- that (0,0) is the top-left corner of the region
276− :: (Reflex t, Monad m, MonadNodeId m, HasVtyWidgetCtx t m)
547+ :: (Reflex t, Monad m, HasInput t m, HasImageWriter t m, HasDisplayRegion t m, HasFocusReader t m)
277 => Dynamic t Region
548 => Dynamic t Region
278 -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
549 -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
281−pane dr foc child = do
552+pane dr foc child = localRegion (const dr) $
282− let reg = current dr
553+ mapImages (imagesInRegion $ current dr) $
283− let subContext ctx = VtyWidgetCtx
554+ localFocus (const foc) $
284− { _vtyWidgetCtx_input = fmapMaybe id $
555+ inputInFocusedRegion >>= \e -> localInput (const e) child
285− attachWith (\(r,f) e -> filterInput r f e)
286− (liftA2 (,) reg (current foc))
287− (_vtyWidgetCtx_input ctx)
288− , _vtyWidgetCtx_focus = liftA2 (&&) (_vtyWidgetCtx_focus ctx) foc
289− , _vtyWidgetCtx_width = _region_width <$> dr
290− , _vtyWidgetCtx_height = _region_height <$> dr
292− let imagesWithinRegion images = liftA2 (\is r -> map (withinImage r) is) images reg
293− localCtx subContext imagesWithinRegion child
295− filterInput :: Region -> Bool -> VtyEvent -> Maybe VtyEvent
296− filterInput (Region l t w h) focused e = case e of
297− V.EvKey _ _ | not focused -> Nothing
298− V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
299− V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
306− , y >= t + h ] = Nothing
308− Just (con (x - l) (y - t))
310−-- | Information about a drag operation
312− { _drag_from :: (Int, Int) -- ^ Where the drag began
313− , _drag_to :: (Int, Int) -- ^ Where the mouse currently is
314− , _drag_button :: V.Button -- ^ Which mouse button is dragging
315− , _drag_modifiers :: [V.Modifier] -- ^ What modifiers are held
316− , _drag_end :: Bool -- ^ Whether the drag ended (the mouse button was released)
318− deriving (Eq, Ord, Show)
320−-- | Converts raw vty mouse drag events into an event stream of 'Drag's
322− :: (Reflex t, MonadFix m, MonadHold t m, HasVtyInput t m)
327− let f :: Maybe Drag -> V.Event -> Maybe Drag
329− V.EvMouseDown x y btn' mods
330− | btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods False
331− | otherwise -> Nothing
333− f (Just (Drag from _ _ mods end)) = \case
334− V.EvMouseDown x y btn' mods'
335− | end && btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods' False
336− | btn == btn' -> Just $ Drag from (x,y) btn mods' False
337− | otherwise -> Nothing -- Ignore other buttons.
338− V.EvMouseUp x y (Just btn')
340− | btn == btn' -> Just $ Drag from (x,y) btn mods True
341− | otherwise -> Nothing
342− V.EvMouseUp x y Nothing -- Terminal doesn't specify mouse up button,
343− -- assume it's the right one.
345− | otherwise -> Just $ Drag from (x,y) btn mods True
347− rec let newDrag = attachWithMaybe f (current dragD) inp
348− dragD <- holdDyn Nothing $ Just <$> newDrag
349− return (fmapMaybe id $ updated dragD)
351−-- | Mouse down events for a particular mouse button
353− :: (Reflex t, Monad m, HasVtyInput t m)
355− -> m (Event t MouseDown)
358− return $ fforMaybe i $ \case
359− V.EvMouseDown x y btn' mods -> if btn == btn'
360− then Just $ MouseDown btn' (x, y) mods
364−-- | Mouse up events for a particular mouse button
366− :: (Reflex t, Monad m, HasVtyInput t m)
367− => m (Event t MouseUp)
370− return $ fforMaybe i $ \case
371− V.EvMouseUp x y btn' -> Just $ MouseUp btn' (x, y)
374−-- | Information about a mouse down event
375−data MouseDown = MouseDown
376− { _mouseDown_button :: V.Button
377− , _mouseDown_coordinates :: (Int, Int)
378− , _mouseDown_modifiers :: [V.Modifier]
380− deriving (Eq, Ord, Show)
382−-- | Information about a mouse up event
383−data MouseUp = MouseUp
384− { _mouseUp_button :: Maybe V.Button
385− , _mouseUp_coordinates :: (Int, Int)
387− deriving (Eq, Ord, Show)
389−-- | Mouse scroll direction
390−data ScrollDirection = ScrollDirection_Up | ScrollDirection_Down
391− deriving (Eq, Ord, Show)
393−-- | Produce an event that fires when the mouse wheel is scrolled
395− :: (Reflex t, Monad m, HasVtyInput t m)
396− => m (Event t ScrollDirection)
398− up <- mouseDown V.BScrollUp
399− down <- mouseDown V.BScrollDown
401− [ ScrollDirection_Up <$ up
402− , ScrollDirection_Down <$ down
405−-- | Type synonym for a key and modifier combination
406−type KeyCombo = (V.Key, [V.Modifier])
408−-- | Emits an event that fires on a particular key press (without modifiers)
409−key :: (Monad m, Reflex t, HasVtyInput t m) => V.Key -> m (Event t KeyCombo)
410−key = keyCombos . Set.singleton . (,[])
412−-- | Emits an event that fires on particular key presses (without modifiers)
413−keys :: (Monad m, Reflex t, HasVtyInput t m) => [V.Key] -> m (Event t KeyCombo)
414−keys = keyCombos . Set.fromList . fmap (,[])
416−-- | Emit an event that fires whenever the provided key combination occurs
418− :: (Reflex t, Monad m, HasVtyInput t m)
420− -> m (Event t KeyCombo)
421−keyCombo = keyCombos . Set.singleton
423−-- | Emit an event that fires whenever any of the provided key combinations occur
425− :: (Reflex t, Monad m, HasVtyInput t m)
427− -> m (Event t KeyCombo)
430− return $ fforMaybe i $ \case
431− V.EvKey k m -> if Set.member (k, m) ks
436−-- | A plain split of the available space into vertically stacked panes.
437−-- No visual separator is built in here.
438−splitV :: (Reflex t, Monad m, MonadNodeId m, HasVtyWidgetCtx t m, HasDisplaySize t m)
439− => Dynamic t (Int -> Int)
440− -- ^ Function used to determine size of first pane based on available size
441− -> Dynamic t (Bool, Bool)
442− -- ^ How to focus the two sub-panes, given that we are focused.
444− -- ^ Widget for first pane
446− -- ^ Widget for second pane
448−splitV sizeFunD focD wA wB = do
451− let regA = Region 0 0 <$> dw <*> (sizeFunD <*> dh)
452− regB = Region 0 <$> (_region_height <$> regA) <*> dw <*> liftA2 (-) dh (_region_height <$> regA)
453− ra <- pane regA (fst <$> focD) wA
454− rb <- pane regB (snd <$> focD) wB
457−-- | A plain split of the available space into horizontally stacked panes.
458−-- No visual separator is built in here.
459−splitH :: (Reflex t, Monad m, MonadNodeId m, HasDisplaySize t m, HasVtyWidgetCtx t m)
460− => Dynamic t (Int -> Int)
461− -- ^ Function used to determine size of first pane based on available size
462− -> Dynamic t (Bool, Bool)
463− -- ^ How to focus the two sub-panes, given that we are focused.
465− -- ^ Widget for first pane
467− -- ^ Widget for second pane
469−splitH sizeFunD focD wA wB = do
472− let regA = Region 0 0 <$> (sizeFunD <*> dw) <*> dh
473− regB = Region <$> (_region_width <$> regA) <*> 0 <*> liftA2 (-) dw (_region_width <$> regA) <*> dh
474− liftA2 (,) (pane regA (fmap fst focD) wA) (pane regB (fmap snd focD) wB)
476−-- | A split of the available space into two parts with a draggable separator.
477−-- Starts with half the space allocated to each, and the first pane has focus.
478−-- Clicking in a pane switches focus.
479−splitVDrag :: (Reflex t, MonadFix m, MonadHold t m, MonadNodeId m, HasDisplaySize t m, HasVtyInput t m, HasVtyWidgetCtx t m)
484−splitVDrag wS wA wB = do
487− h0 <- sample $ current dh -- TODO
488− dragE <- drag V.BLeft
489− let splitter0 = h0 `div` 2
490− rec splitterCheckpoint <- holdDyn splitter0 $ leftmost [fst <$> ffilter snd dragSplitter, resizeSplitter]
491− splitterPos <- holdDyn splitter0 $ leftmost [fst <$> dragSplitter, resizeSplitter]
492− splitterFrac <- holdDyn ((1::Double) / 2) $ ffor (attach (current dh) (fst <$> dragSplitter)) $ \(h, x) ->
493− fromIntegral x / max 1 (fromIntegral h)
494− let dragSplitter = fforMaybe (attach (current splitterCheckpoint) dragE) $
495− \(splitterY, Drag (_, fromY) (_, toY) _ _ end) ->
496− if splitterY == fromY then Just (toY, end) else Nothing
497− regA = Region 0 0 <$> dw <*> splitterPos
498− regS = Region 0 <$> splitterPos <*> dw <*> 1
499− regB = Region 0 <$> (splitterPos + 1) <*> dw <*> (dh - splitterPos - 1)
500− resizeSplitter = ffor (attach (current splitterFrac) (updated dh)) $
501− \(frac, h) -> round (frac * fromIntegral h)
502− focA <- holdDyn True $ leftmost
506− (mA, rA) <- pane regA focA $ withMouseDown wA
507− pane regS (pure False) wS
508− (mB, rB) <- pane regB (not <$> focA) $ withMouseDown wB
511− withMouseDown x = do
512− m <- mouseDown V.BLeft
516−-- | Fill the background with a particular character.
517−fill :: (HasDisplaySize t m, ImageWriter t m) => Char -> m ()
521− let fillImg = current $ liftA2 (\w h -> [V.charFill V.defAttr c w h]) dw dh
524−-- | Fill the background with the bottom
525−hRule :: (HasDisplaySize t m, ImageWriter t m) => BoxStyle -> m ()
526−hRule boxStyle = fill (_boxStyle_s boxStyle)
528−-- | Defines a set of symbols to use to draw the outlines of boxes
529−-- C.f. https://en.wikipedia.org/wiki/Box-drawing_character
530−data BoxStyle = BoxStyle
531− { _boxStyle_nw :: Char
532− , _boxStyle_n :: Char
533− , _boxStyle_ne :: Char
534− , _boxStyle_e :: Char
535− , _boxStyle_se :: Char
536− , _boxStyle_s :: Char
537− , _boxStyle_sw :: Char
538− , _boxStyle_w :: Char
541−instance Default BoxStyle where
557+-- * Misc
542− def = singleBoxStyle
544−-- | A box style that uses hyphens and pipe characters. Doesn't handle
545−-- corners very well.
546−hyphenBoxStyle :: BoxStyle
547−hyphenBoxStyle = BoxStyle '-' '-' '-' '|' '-' '-' '-' '|'
549−-- | A single line box style
550−singleBoxStyle :: BoxStyle
551−singleBoxStyle = BoxStyle '┌' '─' '┐' '│' '┘' '─' '└' '│'
553−-- | A thick single line box style
554−thickBoxStyle :: BoxStyle
555−thickBoxStyle = BoxStyle '┏' '━' '┓' '┃' '┛' '━' '┗' '┃'
557−-- | A double line box style
558−doubleBoxStyle :: BoxStyle
559−doubleBoxStyle = BoxStyle '╔' '═' '╗' '║' '╝' '═' '╚' '║'
561−-- | A single line box style with rounded corners
562−roundedBoxStyle :: BoxStyle
563−roundedBoxStyle = BoxStyle '╭' '─' '╮' '│' '╯' '─' '╰' '│'
565−-- | Draws a titled box in the provided style and a child widget inside of that box
566−boxTitle :: (Monad m, Reflex t, MonadNodeId m, HasDisplaySize t m, ImageWriter t m, HasVtyWidgetCtx t m)
567− => Behavior t BoxStyle
571−boxTitle boxStyle title child = do
574− let boxReg = Region 0 0 <$> dw <*> dh
575− innerReg = Region 1 1 <$> (subtract 2 <$> dw) <*> (subtract 2 <$> dh)
576− tellImages (boxImages <$> boxStyle <*> current boxReg)
577− tellImages (fmap (\r -> [regionBlankImage r]) (current innerReg))
578− pane innerReg (pure True) child
580− boxImages :: BoxStyle -> Region -> [Image]
581− boxImages style (Region left top width height) =
582− let right = left + width - 1
583− bottom = top + height - 1
585− [ withinImage (Region (left + 1) top (width - 2) 1) $
587− hPadText title (_boxStyle_n style) (width - 2)
588− , withinImage (Region right (top + 1) 1 (height - 2)) $
589− V.charFill V.defAttr (_boxStyle_e style) 1 (height - 2)
590− , withinImage (Region (left + 1) bottom (width - 2) 1) $
591− V.charFill V.defAttr (_boxStyle_s style) (width - 2) 1
592− , withinImage (Region left (top + 1) 1 (height - 2)) $
593− V.charFill V.defAttr (_boxStyle_w style) 1 (height - 2)
596− [ withinImage (Region left top 1 1) $
597− V.char V.defAttr (_boxStyle_nw style)
598− , withinImage (Region right top 1 1) $
599− V.char V.defAttr (_boxStyle_ne style)
600− , withinImage (Region right bottom 1 1) $
601− V.char V.defAttr (_boxStyle_se style)
602− , withinImage (Region left bottom 1 1) $
603− V.char V.defAttr (_boxStyle_sw style)
605− in sides ++ if width > 1 && height > 1 then corners else []
606− hPadText :: T.Text -> Char -> Int -> T.Text
607− hPadText t c l = if lt >= l
609− else left <> t <> right
613− mkHalf n = T.replicate (n `div` 2) (T.singleton c)
614− left = mkHalf $ delta + 1
615− right = mkHalf delta
617−-- | A box without a title
618−box :: (Monad m, Reflex t, MonadNodeId m, HasDisplaySize t m, ImageWriter t m, HasVtyWidgetCtx t m)
619− => Behavior t BoxStyle
622−box boxStyle = boxTitle boxStyle mempty
624−-- | A box whose style is static
626− :: (Monad m, Reflex t, MonadNodeId m, HasDisplaySize t m, ImageWriter t m, HasVtyWidgetCtx t m)
630−boxStatic = box . pure
632−-- | Configuration options for displaying "rich" text
633−data RichTextConfig t = RichTextConfig
634− { _richTextConfig_attributes :: Behavior t V.Attr
637−instance Reflex t => Default (RichTextConfig t) where
638− def = RichTextConfig $ pure V.defAttr
640−-- | A widget that displays text with custom time-varying attributes
642− :: (Reflex t, Monad m, HasDisplaySize t m, ImageWriter t m)
648− let img = (\w a s -> [wrapText w a s])
650− <*> _richTextConfig_attributes cfg
654− wrapText maxWidth attrs = V.vertCat
655− . concatMap (fmap (V.string attrs . T.unpack) . TZ.wrapWithOffset maxWidth 0)
658−-- | Renders text, wrapped to the container width
660− :: (Reflex t, Monad m, HasDisplaySize t m, ImageWriter t m)
665−-- | Scrollable text widget. The output pair exposes the current scroll position and total number of lines (including those
668− :: forall t m. (Reflex t, MonadHold t m, MonadFix m, HasDisplaySize t m, HasVtyInput t m, ImageWriter t m)
670− -- ^ Number of lines to scroll by
672− -> m (Behavior t (Int, Int))
673− -- ^ (Current scroll position, total number of lines)
674−scrollableText scrollBy t = do
676− let imgs = wrap <$> current dw <*> t
678− kdown <- key V.KDown
680− let requestedScroll :: Event t Int
681− requestedScroll = leftmost
685− ScrollDirection_Up -> (-1)
686− ScrollDirection_Down -> 1
689− updateLine maxN delta ix = min (max 0 (ix + delta)) maxN
690− lineIndex :: Dynamic t Int <- foldDyn (\(maxN, delta) ix -> updateLine (maxN - 1) delta ix) 0 $
691− attach (length <$> imgs) requestedScroll
692− tellImages $ fmap ((:[]) . V.vertCat) $ drop <$> current lineIndex <*> imgs
693− return $ (,) <$> ((+) <$> current lineIndex <*> pure 1) <*> (length <$> imgs)
695− wrap maxWidth = concatMap (fmap (V.string V.defAttr . T.unpack) . TZ.wrapWithOffset maxWidth 0) . T.split (=='\n')
697−-- | Renders any behavior whose value can be converted to
700− :: (Reflex t, Monad m, Show a, HasDisplaySize t m, ImageWriter t m)
703−display a = text $ T.pack . show <$> a
705-- | A widget that draws nothing
559-- | A widget that draws nothing
706blank :: Monad m => m ()
560blank :: Monad m => m ()