@@ -2,159 +2,41 @@
2Module: Reflex.Vty.Widget
2Module: Reflex.Vty.Widget
3Description: Basic set of widgets and building blocks for reflex-vty applications
3Description: Basic set of widgets and building blocks for reflex-vty applications
5−{-# LANGUAGE DefaultSignatures #-}
6−{-# LANGUAGE DeriveFunctor #-}
7−{-# LANGUAGE FlexibleContexts #-}
8−{-# LANGUAGE FlexibleInstances #-}
9−{-# LANGUAGE FunctionalDependencies #-}
10−{-# LANGUAGE GeneralizedNewtypeDeriving #-}
11−{-# LANGUAGE LambdaCase #-}
12−{-# LANGUAGE RankNTypes #-}
13−{-# LANGUAGE RecursiveDo #-}
14−{-# LANGUAGE ScopedTypeVariables #-}
15−{-# LANGUAGE StandaloneDeriving #-}
16−{-# LANGUAGE TupleSections #-}
17−{-# LANGUAGE TypeFamilies #-}
18−{-# LANGUAGE UndecidableInstances #-}
5+{-# Language UndecidableInstances #-}
20−module Reflex.Vty.Widget
7+module Reflex.Vty.Widget where
27− , mainWidgetWithHandle
42− , ScrollDirection(..)
70import Control.Applicative (liftA2)
9import Control.Applicative (liftA2)
71import Control.Monad.Fix (MonadFix)
10import Control.Monad.Fix (MonadFix)
72−import Control.Monad.Reader
11+import Control.Monad.IO.Class (MonadIO)
12+import Control.Monad.Morph
13+import Control.Monad.NodeId
14+import Control.Monad.Reader (ReaderT, ask, local, runReaderT)
15+import Control.Monad.Ref
73−import Control.Monad.Trans (lift)
16+import Control.Monad.Trans (MonadTrans, lift)
74−import Data.Default (Default(..))
75import Data.Set (Set)
17import Data.Set (Set)
76import qualified Data.Set as Set
18import qualified Data.Set as Set
77−import Data.Text (Text)
78−import qualified Data.Text as T
79−import qualified Data.Text.Zipper as TZ
80import Graphics.Vty (Image)
19import Graphics.Vty (Image)
81import qualified Graphics.Vty as V
20import qualified Graphics.Vty as V
82import Reflex
21import Reflex
83import Reflex.Class ()
22import Reflex.Class ()
84import Reflex.Host.Class (MonadReflexCreateTrigger)
23import Reflex.Host.Class (MonadReflexCreateTrigger)
86import Reflex.Vty.Host
24import Reflex.Vty.Host
88−import Control.Monad.NodeId
26+-- * Running a vty application
90−-- | The context within which a 'VtyWidget' runs
91−data VtyWidgetCtx t = VtyWidgetCtx
92− { _vtyWidgetCtx_width :: Dynamic t Int
93− -- ^ The width of the region allocated to the widget.
94− , _vtyWidgetCtx_height :: Dynamic t Int
95− -- ^ The height of the region allocated to the widget.
96− , _vtyWidgetCtx_focus :: Dynamic t Bool
97− -- ^ Whether the widget should behave as if it has focus for keyboard input.
98− , _vtyWidgetCtx_input :: Event t VtyEvent
99− -- ^ User input events that the widget's parent chooses to share. These will generally
100− -- be filtered for relevance:
101− -- * Keyboard inputs are restricted to focused widgets
102− -- * Mouse inputs are restricted to the region in which the widget resides and are
103− -- translated into its internal coordinates.
106−-- | The output of a 'VtyWidget'
107−data VtyWidgetOut t = VtyWidgetOut
108− { _vtyWidgetOut_shutdown :: Event t ()
111−instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (VtyWidget t m) where
112− runWithReplace a0 a' = VtyWidget $ runWithReplace (unVtyWidget a0) $ fmap unVtyWidget a'
113− traverseIntMapWithKeyWithAdjust f dm0 dm' = VtyWidget $
114− traverseIntMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
115− traverseDMapWithKeyWithAdjust f dm0 dm' = VtyWidget $ do
116− traverseDMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
117− traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = VtyWidget $ do
118− traverseDMapWithKeyWithAdjustWithMove (\k v -> unVtyWidget (f k v)) dm0 dm'
120−-- | A widget that can read its context and produce image output
121−newtype VtyWidget t m a = VtyWidget
122− { unVtyWidget :: BehaviorWriterT t [Image] (ReaderT (VtyWidgetCtx t) m) a
134− , MonadReflexCreateTrigger t
138−deriving instance PerformEvent t m => PerformEvent t (VtyWidget t m)
139−instance MonadTrans (VtyWidget t) where
140− lift f = VtyWidget $ lift $ lift f
142−instance MonadNodeId m => MonadNodeId (VtyWidget t m) where
143− getNextNodeId = VtyWidget $ do
144− lift $ lift $ getNextNodeId
146−-- | Runs a 'VtyWidget' with a given context
148− :: (Reflex t, MonadNodeId m)
151− -> m (a, Behavior t [Image])
152−runVtyWidget ctx w = runReaderT (runBehaviorWriterT (unVtyWidget w)) ctx
154−-- | 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
155mainWidgetWithHandle
29mainWidgetWithHandle
157− -> (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
32+ ( MonadVtyApp t m
35+ , HasDisplayRegion t m
159mainWidgetWithHandle vty child =
41mainWidgetWithHandle vty child =
160 runVtyAppWithHandle vty $ \dr0 inp -> do
42 runVtyAppWithHandle vty $ \dr0 inp -> do
@@ -164,71 +46,178 @@ mainWidgetWithHandle vty child =
164 let inp' = fforMaybe inp $ \case
46 let inp' = fforMaybe inp $ \case
165 V.EvResize {} -> Nothing
47 V.EvResize {} -> Nothing
166 x -> Just x
48 x -> Just x
167− let ctx = VtyWidgetCtx
49+ (shutdown, images) <- runThemeReader (constant V.defAttr) $
168− { _vtyWidgetCtx_width = fmap fst size
50+ runFocusReader (pure True) $
169− , _vtyWidgetCtx_height = fmap snd size
51+ runDisplayRegion (fmap (\(w, h) -> Region 0 0 w h) size) $
170− , _vtyWidgetCtx_input = inp'
52+ runImageWriter $
171− , _vtyWidgetCtx_focus = constDyn True
53+ runNodeIdT $
172− }
54+ runInput inp' $ do
173− (shutdown, images) <- runNodeIdT $ runVtyWidget ctx $ do
174− 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]
176 return $ VtyResult
57 return $ VtyResult
177 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
58 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
178 , _vtyResult_shutdown = shutdown
59 , _vtyResult_shutdown = shutdown
62+-- | The output of a vty widget
63+data VtyWidgetOut t = VtyWidgetOut
64+ { _vtyWidgetOut_shutdown :: Event t ()
181-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
67-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
182mainWidget
68mainWidget
183− :: (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
70+ ( MonadVtyApp t m
73+ , HasDisplayRegion t m
185mainWidget child = do
79mainWidget child = do
186 vty <- getDefaultVty
80 vty <- getDefaultVty
187 mainWidgetWithHandle vty child
81 mainWidgetWithHandle vty child
189−-- | A class for things that know their own display size dimensions
83+-- * Input Events
190−class (Reflex t, Monad m) => HasDisplaySize t m | m -> t where
191− -- | Retrieve the display width (columns)
192− displayWidth :: m (Dynamic t Int)
193− default displayWidth :: (f m' ~ m, MonadTrans f, HasDisplaySize t m') => m (Dynamic t Int)
194− displayWidth = lift displayWidth
195− -- | Retrieve the display height (rows)
196− displayHeight :: m (Dynamic t Int)
197− default displayHeight :: (f m' ~ m, MonadTrans f, HasDisplaySize t m') => m (Dynamic t Int)
198− displayHeight = lift displayHeight
200−instance (Reflex t, Monad m) => HasDisplaySize t (VtyWidget t m) where
201− displayWidth = VtyWidget . lift $ asks _vtyWidgetCtx_width
202− displayHeight = VtyWidget . lift $ asks _vtyWidgetCtx_height
204−instance HasDisplaySize t m => HasDisplaySize t (ReaderT x m)
205−instance HasDisplaySize t m => HasDisplaySize t (BehaviorWriterT t x m)
206−instance HasDisplaySize t m => HasDisplaySize t (DynamicWriterT t x m)
207−instance HasDisplaySize t m => HasDisplaySize t (EventWriterT t x m)
209−instance HasDisplaySize t m => HasDisplaySize t (NodeIdT m)
211-- | A class for things that can receive vty events as input
85-- | A class for things that can receive vty events as input
212−class HasVtyInput t m | m -> t where
86+class HasInput t m | m -> t where
213 input :: m (Event t VtyEvent)
87 input :: m (Event t VtyEvent)
88+ default input :: (f m' ~ m, Monad m', MonadTrans f, HasInput t m') => m (Event t VtyEvent)
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
215−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
216− 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
148+-- ** Filtering input
218−-- | A class for things that can dynamically gain and lose focus
150+-- | Type synonym for a key and modifier combination
219−class HasFocus t m | m -> t where
151+type KeyCombo = (V.Key, [V.Modifier])
220− focus :: m (Dynamic t Bool)
222−instance (Reflex t, Monad m) => HasFocus t (VtyWidget t m) where
153+-- | Emits an event that fires on a particular key press (without modifiers)
223− focus = VtyWidget . lift $ asks _vtyWidgetCtx_focus
154+key :: (Monad m, Reflex t, HasInput t m) => V.Key -> m (Event t KeyCombo)
155+key = keyCombos . Set.singleton . (,[])
225−-- | A class for widgets that can produce images to draw to the display
157+-- | Emits an event that fires on particular key presses (without modifiers)
226−class (Reflex t, Monad m) => ImageWriter t m | m -> t where
158+keys :: (Monad m, Reflex t, HasInput t m) => [V.Key] -> m (Event t KeyCombo)
227− -- | Send images upstream for rendering
159+keys = keyCombos . Set.fromList . fmap (,[])
228− tellImages :: Behavior t [Image] -> m ()
230−instance (Monad m, Reflex t) => ImageWriter t (BehaviorWriterT t [Image] m) where
161+-- | Emit an event that fires whenever the provided key combination occurs
231− tellImages = tellBehavior
162+keyCombo
163+ :: (Reflex t, Monad m, HasInput t m)
165+ -> m (Event t KeyCombo)
166+keyCombo = keyCombos . Set.singleton
168+-- | Emit an event that fires whenever any of the provided key combinations occur
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
233-- | A chunk of the display area
222-- | A chunk of the display area
234data Region = Region
223data Region = Region
@@ -239,451 +228,334 @@ data Region = Region
240 deriving (Show, Read, Eq, Ord)
229 deriving (Show, Read, Eq, Ord)
242−-- | A dynamic chunk of the display area
231+-- | A region that occupies no space.
243−data DynRegion t = DynRegion
232+nilRegion :: Region
244− { _dynRegion_left :: Dynamic t Int
233+nilRegion = Region 0 0 0 0
245− , _dynRegion_top :: Dynamic t Int
246− , _dynRegion_width :: Dynamic t Int
247− , _dynRegion_height :: Dynamic t Int
250-- | The width and height of a 'Region'
235-- | The width and height of a 'Region'
251regionSize :: Region -> (Int, Int)
236regionSize :: Region -> (Int, Int)
252regionSize (Region _ _ w h) = (w, h)
237regionSize (Region _ _ w h) = (w, h)
254-- | Produces an 'Image' that fills a region with space characters
239-- | Produces an 'Image' that fills a region with space characters
255−regionBlankImage :: Region -> Image
240+regionBlankImage :: V.Attr -> Region -> Image
256−regionBlankImage r@(Region _ _ width height) =
241+regionBlankImage attr r@(Region _ _ width height) =
257− withinImage r $ V.charFill V.defAttr ' ' width height
242+ withinImage r $ V.charFill attr ' ' width height
259−-- | A behavior of the current display area represented by a 'DynRegion'
244+-- | A class for things that know their own display size dimensions
260−currentRegion :: Reflex t => DynRegion t -> Behavior t Region
245+class (Reflex t, Monad m) => HasDisplayRegion t m | m -> t where
261−currentRegion (DynRegion l t w h) = Region <$> current l <*> current t <*> current w <*> current h
246+ -- | Retrieve the display region
247+ askRegion :: m (Dynamic t Region)
248+ default askRegion :: (f m' ~ m, MonadTrans f, HasDisplayRegion t m') => m (Dynamic t Region)
249+ askRegion = lift askRegion
250+ -- | Run an action in a local region, by applying a transformation to the region
251+ localRegion :: (Dynamic t Region -> Dynamic t Region) -> m a -> m a
252+ default localRegion :: (f m' ~ m, Monad m', MFunctor f, HasDisplayRegion t m') => (Dynamic t Region -> Dynamic t Region) -> m a -> m a
253+ localRegion f = hoist (localRegion f)
255+-- | Retrieve the display width
256+displayWidth :: HasDisplayRegion t m => m (Dynamic t Int)
257+displayWidth = fmap _region_width <$> 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 }
263−-- | Translates and crops an 'Image' so that it is contained by
283+instance (Monad m, Reflex t) => HasDisplayRegion t (DisplayRegion t m) where
264−-- the given 'Region'.
284+ askRegion = DisplayRegion ask
265−withinImage
285+ localRegion f = DisplayRegion . local f . unDisplayRegion
269−withinImage (Region left top width height)
270− | width < 0 || height < 0 = withinImage (Region left top 0 0)
271− | otherwise = V.translate left top . V.crop width height
273−-- | Low-level widget combinator that runs a child 'VtyWidget' within
287+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (DisplayRegion t m)
274−-- a given region and context. This widget filters and modifies the input
288+deriving instance NotReady t m => NotReady t (DisplayRegion t m)
275−-- that the child widget receives such that:
289+deriving instance PerformEvent t m => PerformEvent t (DisplayRegion t m)
276−-- * unfocused widgets receive no key events
290+deriving instance PostBuild t m => PostBuild t (DisplayRegion t m)
277−-- * mouse inputs outside the region are ignored
291+deriving instance TriggerEvent t m => TriggerEvent t (DisplayRegion t m)
278−-- * mouse inputs inside the region have their coordinates translated such
292+instance HasImageWriter t m => HasImageWriter t (DisplayRegion t m)
279−-- that (0,0) is the top-left corner of the region
293+instance HasFocusReader t m => HasFocusReader t (DisplayRegion t m)
281− :: (Reflex t, Monad m, MonadNodeId m)
283− -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
286−pane dr foc child = VtyWidget $ do
288− let reg = currentRegion dr
289− let ctx' = VtyWidgetCtx
290− { _vtyWidgetCtx_input = leftmost -- TODO: think about this leftmost more.
292− attachWith (\(r,f) e -> filterInput r f e)
293− (liftA2 (,) reg (current foc))
294− (_vtyWidgetCtx_input ctx)
296− , _vtyWidgetCtx_focus = liftA2 (&&) (_vtyWidgetCtx_focus ctx) foc
297− , _vtyWidgetCtx_width = _dynRegion_width dr
298− , _vtyWidgetCtx_height = _dynRegion_height dr
300− (result, images) <- lift . lift $ runVtyWidget ctx' child
301− let images' = liftA2 (\r is -> map (withinImage r) is) reg images
305− filterInput :: Region -> Bool -> VtyEvent -> Maybe VtyEvent
306− filterInput (Region l t w h) focused e = case e of
307− V.EvKey _ _ | not focused -> Nothing
308− V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
309− V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
316− , y >= t + h ] = Nothing
318− Just (con (x - l) (y - t))
320−-- | Information about a drag operation
322− { _drag_from :: (Int, Int) -- ^ Where the drag began
323− , _drag_to :: (Int, Int) -- ^ Where the mouse currently is
324− , _drag_button :: V.Button -- ^ Which mouse button is dragging
325− , _drag_modifiers :: [V.Modifier] -- ^ What modifiers are held
326− , _drag_end :: Bool -- ^ Whether the drag ended (the mouse button was released)
328− deriving (Eq, Ord, Show)
330−-- | Converts raw vty mouse drag events into an event stream of 'Drag's
332− :: (Reflex t, MonadFix m, MonadHold t m)
334− -> VtyWidget t m (Event t Drag)
337− let f :: Maybe Drag -> V.Event -> Maybe Drag
339− V.EvMouseDown x y btn' mods
340− | btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods False
341− | otherwise -> Nothing
343− f (Just (Drag from _ _ mods end)) = \case
344− V.EvMouseDown x y btn' mods'
345− | end -> Just $ Drag (x,y) (x,y) btn' mods' False
346− | btn == btn' -> Just $ Drag from (x,y) btn mods' False
347− | otherwise -> Nothing -- Ignore other buttons.
348− V.EvMouseUp x y (Just btn')
350− | btn == btn' -> Just $ Drag from (x,y) btn mods True
351− | otherwise -> Nothing
352− V.EvMouseUp x y Nothing -- Terminal doesn't specify mouse up button,
353− -- assume it's the right one.
355− | otherwise -> Just $ Drag from (x,y) btn mods True
357− rec let newDrag = attachWithMaybe f (current dragD) inp
358− dragD <- holdDyn Nothing $ Just <$> newDrag
359− return (fmapMaybe id $ updated dragD)
361−-- | Mouse down events for a particular mouse button
363− :: (Reflex t, Monad m)
365− -> VtyWidget t m (Event t MouseDown)
368− return $ fforMaybe i $ \case
369− V.EvMouseDown x y btn' mods -> if btn == btn'
370− then Just $ MouseDown btn' (x, y) mods
374−-- | Mouse up events for a particular mouse button
295+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (DisplayRegion t m) where
375−mouseUp
296+ runWithReplace (DisplayRegion a) e = DisplayRegion $ runWithReplace a $ fmap unDisplayRegion e
376− :: (Reflex t, Monad m)
297+ traverseIntMapWithKeyWithAdjust f m e = DisplayRegion $ traverseIntMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
377− => VtyWidget t m (Event t MouseUp)
298+ traverseDMapWithKeyWithAdjust f m e = DisplayRegion $ traverseDMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
378−mouseUp = do
299+ traverseDMapWithKeyWithAdjustWithMove f m e = DisplayRegion $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unDisplayRegion $ f k v) m e
380− return $ fforMaybe i $ \case
381− V.EvMouseUp x y btn' -> Just $ MouseUp btn' (x, y)
384−-- | Information about a mouse down event
301+instance MonadTrans (DisplayRegion t) where
385−data MouseDown = MouseDown
302+ lift = DisplayRegion . lift
386− { _mouseDown_button :: V.Button
387− , _mouseDown_coordinates :: (Int, Int)
388− , _mouseDown_modifiers :: [V.Modifier]
390− deriving (Eq, Ord, Show)
392−-- | Information about a mouse up event
304+instance MFunctor (DisplayRegion t) where
393−data MouseUp = MouseUp
305+ hoist f = DisplayRegion . hoist f . unDisplayRegion
394− { _mouseUp_button :: Maybe V.Button
395− , _mouseUp_coordinates :: (Int, Int)
397− deriving (Eq, Ord, Show)
399−-- | Mouse scroll direction
307+instance MonadNodeId m => MonadNodeId (DisplayRegion t m)
400−data ScrollDirection = ScrollDirection_Up | ScrollDirection_Down
401− deriving (Eq, Ord, Show)
403−-- | Produce an event that fires when the mouse wheel is scrolled
309+-- | Run a 'DisplayRegion' action with a given 'Region'
404−mouseScroll
310+runDisplayRegion
405 :: (Reflex t, Monad m)
311 :: (Reflex t, Monad m)
406− => VtyWidget t m (Event t ScrollDirection)
312+ => Dynamic t Region
407−mouseScroll = do
313+ -> DisplayRegion t m a
408− up <- mouseDown V.BScrollUp
314+ -> m a
409− down <- mouseDown V.BScrollDown
315+runDisplayRegion r = flip runReaderT r . unDisplayRegion
411− [ ScrollDirection_Up <$ up
412− , ScrollDirection_Down <$ down
415−-- | Type synonym for a key and modifier combination
317+-- * Getting focus state
416−type KeyCombo = (V.Key, [V.Modifier])
418−-- | Emits an event that fires on a particular key press (without modifiers)
319+-- | A class for things that can dynamically gain and lose focus
419−key :: (Monad m, Reflex t) => V.Key -> VtyWidget t m (Event t KeyCombo)
320+class (Reflex t, Monad m) => HasFocusReader t m | m -> t where
420−key = keyCombos . Set.singleton . (,[])
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 }
422−-- | Emits an event that fires on particular key presses (without modifiers)
348+instance (Monad m, Reflex t) => HasFocusReader t (FocusReader t m) where
423−keys :: (Monad m, Reflex t) => [V.Key] -> VtyWidget t m (Event t KeyCombo)
349+ focus = FocusReader ask
424−keys = keyCombos . Set.fromList . fmap (,[])
350+ localFocus f = FocusReader . local f . unFocusReader
426−-- | Emit an event that fires whenever the provided key combination occurs
352+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (FocusReader t m)
427−keyCombo
353+deriving instance NotReady t m => NotReady t (FocusReader t m)
428− :: (Reflex t, Monad m)
354+deriving instance PerformEvent t m => PerformEvent t (FocusReader t m)
429− => KeyCombo
355+deriving instance PostBuild t m => PostBuild t (FocusReader t m)
430− -> VtyWidget t m (Event t KeyCombo)
356+deriving instance TriggerEvent t m => TriggerEvent t (FocusReader t m)
431−keyCombo = keyCombos . Set.singleton
357+instance HasImageWriter t m => HasImageWriter t (FocusReader t m)
433−-- | Emit an event that fires whenever any of the provided key combinations occur
359+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (FocusReader t m) where
434−keyCombos
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
435 :: (Reflex t, Monad m)
375 :: (Reflex t, Monad m)
436− => Set KeyCombo
376+ => Dynamic t Bool
437− -> VtyWidget t m (Event t KeyCombo)
377+ -> FocusReader t m a
438−keyCombos ks = do
378+ -> m a
439− i <- input
379+runFocusReader b = flip runReaderT b . unFocusReader
440− return $ fforMaybe i $ \case
441− V.EvKey k m -> if Set.member (k, m) ks
446−-- | A plain split of the available space into vertically stacked panes.
381+-- * "Image" output
447−-- No visual separator is built in here.
448−splitV :: (Reflex t, Monad m, MonadNodeId m)
449− => Dynamic t (Int -> Int)
450− -- ^ Function used to determine size of first pane based on available size
451− -> Dynamic t (Bool, Bool)
452− -- ^ How to focus the two sub-panes, given that we are focused.
454− -- ^ Widget for first pane
456− -- ^ Widget for second pane
457− -> VtyWidget t m (a,b)
458−splitV sizeFunD focD wA wB = do
461− let regA = DynRegion
462− { _dynRegion_left = pure 0
463− , _dynRegion_top = pure 0
464− , _dynRegion_width = dw
465− , _dynRegion_height = sizeFunD <*> dh
468− { _dynRegion_left = pure 0
469− , _dynRegion_top = _dynRegion_height regA
470− , _dynRegion_width = dw
471− , _dynRegion_height = liftA2 (-) dh (_dynRegion_height regA)
473− ra <- pane regA (fst <$> focD) wA
474− rb <- pane regB (snd <$> focD) wB
477−-- | A split of the available space into two parts with a draggable separator.
478−-- Starts with half the space allocated to each, and the first pane has focus.
479−-- Clicking in a pane switches focus.
480−splitVDrag :: (Reflex t, MonadFix m, MonadHold t m, MonadNodeId m)
484− -> VtyWidget t m (a,b)
485−splitVDrag wS wA wB = do
488− h0 <- sample $ current dh -- TODO
489− dragE <- drag V.BLeft
490− let splitter0 = h0 `div` 2
491− rec splitterCheckpoint <- holdDyn splitter0 $ leftmost [fst <$> ffilter snd dragSplitter, resizeSplitter]
492− splitterPos <- holdDyn splitter0 $ leftmost [fst <$> dragSplitter, resizeSplitter]
493− splitterFrac <- holdDyn ((1::Double) / 2) $ ffor (attach (current dh) (fst <$> dragSplitter)) $ \(h, x) ->
494− fromIntegral x / (max 1 (fromIntegral h))
495− let dragSplitter = fforMaybe (attach (current splitterCheckpoint) dragE) $
496− \(splitterY, Drag (_, fromY) (_, toY) _ _ end) ->
497− if splitterY == fromY then Just (toY, end) else Nothing
498− regA = DynRegion 0 0 dw splitterPos
499− regS = DynRegion 0 splitterPos dw 1
500− regB = DynRegion 0 (splitterPos + 1) dw (dh - splitterPos - 1)
501− resizeSplitter = ffor (attach (current splitterFrac) (updated dh)) $
502− \(frac, h) -> round (frac * fromIntegral h)
503− focA <- holdDyn True $ leftmost
507− (mA, rA) <- pane regA focA $ withMouseDown wA
508− pane regS (pure False) wS
509− (mB, rB) <- pane regB (not <$> focA) $ withMouseDown wB
512− withMouseDown x = do
513− m <- mouseDown V.BLeft
517−-- | Fill the background with a particular character.
518−fill :: (Reflex t, Monad m) => Char -> VtyWidget t m ()
522− let fillImg = current $ liftA2 (\w h -> [V.charFill V.defAttr c w h]) dw dh
525−-- | Fill the background with the bottom
526−hRule :: (Reflex t, Monad m) => BoxStyle -> VtyWidget t m ()
527−hRule boxStyle = fill (_boxStyle_s boxStyle)
529−-- | Defines a set of symbols to use to draw the outlines of boxes
530−-- C.f. https://en.wikipedia.org/wiki/Box-drawing_character
531−data BoxStyle = BoxStyle
532− { _boxStyle_nw :: Char
533− , _boxStyle_n :: Char
534− , _boxStyle_ne :: Char
535− , _boxStyle_e :: Char
536− , _boxStyle_se :: Char
537− , _boxStyle_s :: Char
538− , _boxStyle_sw :: Char
539− , _boxStyle_w :: Char
542−instance Default BoxStyle where
383+-- | A class for widgets that can produce images to draw to the display
543− def = singleBoxStyle
384+class (Reflex t, Monad m) => HasImageWriter t m | m -> t where
544−
385+ -- | Send images upstream for rendering
545−-- | A box style that uses hyphens and pipe characters. Doesn't handle
386+ tellImages :: Behavior t [Image] -> m ()
546−-- corners very well.
387+ default tellImages :: (f m' ~ m, Monad m', MonadTrans f, HasImageWriter t m') => Behavior t [Image] -> m ()
547−hyphenBoxStyle :: BoxStyle
388+ tellImages = lift . tellImages
548−hyphenBoxStyle = BoxStyle '-' '-' '-' '|' '-' '-' '-' '|'
389+ -- | Apply a transformation to the images produced by the child actions
549−
390+ mapImages :: (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
550−-- | A single line box style
391+ default mapImages :: (f m' ~ m, Monad m', MFunctor f, HasImageWriter t m') => (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
551−singleBoxStyle :: BoxStyle
392+ mapImages f = hoist (mapImages f)
552−singleBoxStyle = BoxStyle '┌' '─' '┐' '│' '┘' '─' '└' '│'
393+
553−
394+-- | A widget that can produce images to draw onto the display
554−-- | A thick single line box style
395+newtype ImageWriter t m a = ImageWriter
555−thickBoxStyle :: BoxStyle
396+ { unImageWriter :: BehaviorWriterT t [Image] m a }
556−thickBoxStyle = BoxStyle '┏' '━' '┓' '┃' '┛' '━' '┗' '┃'
397+ deriving
558−-- | A double line box style
399+ , Applicative
559−doubleBoxStyle :: BoxStyle
400+ , Monad
560−doubleBoxStyle = BoxStyle '╔' '═' '╗' '║' '╝' '═' '╚' '║'
401+ , MonadFix
562−-- | A single line box style with rounded corners
403+ , MonadIO
563−roundedBoxStyle :: BoxStyle
404+ , MonadRef
564−roundedBoxStyle = BoxStyle '╭' '─' '╮' '│' '╯' '─' '╰' '│'
405+ , MonadReflexCreateTrigger t
566−-- | Draws a box in the provided style and a child widget inside of that box
407+ , NotReady t
567−box :: (Monad m, Reflex t, MonadNodeId m)
408+ , PerformEvent t
568− => Behavior t BoxStyle
409+ , PostBuild t
569− -> VtyWidget t m a
410+ , TriggerEvent t
570− -> VtyWidget t m a
411+ )
571−box boxStyle child = do
412+
572− dh <- displayHeight
413+instance MonadTrans (ImageWriter t) where
573− dw <- displayWidth
414+ lift = ImageWriter . lift
574− let boxReg = DynRegion (pure 0) (pure 0) dw dh
415+
575− innerReg = DynRegion (pure 1) (pure 1) (subtract 2 <$> dw) (subtract 2 <$> dh)
416+instance MFunctor (ImageWriter t) where
576− tellImages (boxImages <$> boxStyle <*> currentRegion boxReg)
417+ hoist f = ImageWriter . (hoist f) . unImageWriter
577− tellImages (fmap (\r -> [regionBlankImage r]) (currentRegion innerReg))
418+
578− pane innerReg (pure True) child
419+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (ImageWriter t m) where
579− where
420+ runWithReplace (ImageWriter a) e = ImageWriter $ runWithReplace a $ fmap unImageWriter e
580− boxImages :: BoxStyle -> Region -> [Image]
421+ traverseIntMapWithKeyWithAdjust f m e = ImageWriter $ traverseIntMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
581− boxImages style (Region left top width height) =
422+ traverseDMapWithKeyWithAdjust f m e = ImageWriter $ traverseDMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
582− let right = left + width - 1
423+ traverseDMapWithKeyWithAdjustWithMove f m e = ImageWriter $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unImageWriter $ f k v) m e
583− bottom = top + height - 1
585− [ withinImage (Region (left + 1) top (width - 2) 1) $
586− V.charFill V.defAttr (_boxStyle_n style) (width - 2) 1
587− , withinImage (Region right (top + 1) 1 (height - 2)) $
588− V.charFill V.defAttr (_boxStyle_e style) 1 (height - 2)
589− , withinImage (Region (left + 1) bottom (width - 2) 1) $
590− V.charFill V.defAttr (_boxStyle_s style) (width - 2) 1
591− , withinImage (Region left (top + 1) 1 (height - 2)) $
592− V.charFill V.defAttr (_boxStyle_w style) 1 (height - 2)
595− [ withinImage (Region left top 1 1) $
596− V.char V.defAttr (_boxStyle_nw style)
597− , withinImage (Region right top 1 1) $
598− V.char V.defAttr (_boxStyle_ne style)
599− , withinImage (Region right bottom 1 1) $
600− V.char V.defAttr (_boxStyle_se style)
601− , withinImage (Region left bottom 1 1) $
602− V.char V.defAttr (_boxStyle_sw style)
604− in sides ++ if width > 1 && height > 1 then corners else []
606−-- | A box whose style is static
608− :: (Reflex t, Monad m, MonadNodeId m)
612−boxStatic = box . pure
614−-- | Configuration options for displaying "rich" text
615−data RichTextConfig t = RichTextConfig
616− { _richTextConfig_attributes :: Behavior t V.Attr
619−instance Reflex t => Default (RichTextConfig t) where
425+instance HasImageWriter t m => HasImageWriter t (ReaderT x m)
620− def = RichTextConfig $ pure V.defAttr
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)
622−-- | A widget that displays text with custom time-varying attributes
431+instance (Monad m, Reflex t) => HasImageWriter t (ImageWriter t m) where
623−richText
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
624 :: (Reflex t, Monad m)
443 :: (Reflex t, Monad m)
625− => RichTextConfig t
444+ => ImageWriter t m a
626− -> Behavior t Text
445+ -> m (a, Behavior t [Image])
627− -> VtyWidget t m ()
446+runImageWriter = runBehaviorWriterT . unImageWriter
628−richText cfg t = do
447+
629− dw <- displayWidth
448+-- * Theming
630− let img = (\w a s -> [wrapText w a s])
449+
631− <$> current dw
450+-- | A class for things that can be visually styled
632− <*> _richTextConfig_attributes cfg
451+class (Reflex t, Monad m) => HasTheme t m | m -> t where
633− <*> t
452+ theme :: m (Behavior t V.Attr)
634− tellImages img
453+ default theme :: (f m' ~ m, Monad m', MonadTrans f, HasTheme t m') => m (Behavior t V.Attr)
635− where
454+ theme = lift theme
636− wrapText maxWidth attrs = V.vertCat
455+ localTheme :: (Behavior t V.Attr -> Behavior t V.Attr) -> m a -> m a
637− . concatMap (fmap (V.string attrs . T.unpack) . TZ.wrapWithOffset maxWidth 0)
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
638− . T.split (=='\n')
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
640−-- | Renders text, wrapped to the container width
503+instance MFunctor (ThemeReader t) where
641−text
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
642 :: (Reflex t, Monad m)
510 :: (Reflex t, Monad m)
643− => Behavior t Text
511+ => Behavior t V.Attr
644− -> VtyWidget t m ()
512+ -> ThemeReader t m a
645−text = richText def
513+ -> m a
646−
514+runThemeReader b = flip runReaderT b . unThemeReader
647−-- | Scrollable text widget. The output pair exposes the current scroll position and total number of lines (including those
515+
648−-- that are hidden)
516+
649−scrollableText
517+-- ** Manipulating images
650− :: forall t m. (Reflex t, MonadHold t m, MonadFix m)
518+
651− => Event t Int
519+-- | Translates and crops an 'Image' so that it is contained by
652− -- ^ Number of lines to scroll by
520+-- the given 'Region'.
653− -> Behavior t Text
521+withinImage
654− -> VtyWidget t m (Behavior t (Int, Int))
522+ :: Region
655− -- ^ (Current scroll position, total number of lines)
523+ -> Image
656−scrollableText scrollBy t = do
524+ -> Image
657− dw <- displayWidth
525+withinImage (Region left top width height)
658− let imgs = wrap <$> current dw <*> t
526+ | width < 0 || height < 0 = withinImage (Region left top 0 0)
659− kup <- key V.KUp
527+ | otherwise = V.translate left top . V.crop width height
660− kdown <- key V.KDown
528+
661− m <- mouseScroll
529+-- | Crop a behavior of images to a behavior of regions. See 'withinImage'.
662− let requestedScroll :: Event t Int
530+imagesInRegion
663− requestedScroll = leftmost
531+ :: Reflex t
664− [ 1 <$ kdown
532+ => Behavior t Region
665− , (-1) <$ kup
533+ -> Behavior t [Image]
666− , ffor m $ \case
534+ -> Behavior t [Image]
667− ScrollDirection_Up -> (-1)
535+imagesInRegion reg = liftA2 (\r is -> map (withinImage r) is) reg
668− ScrollDirection_Down -> 1
536+
669− , scrollBy
537+-- * Running sub-widgets
671− updateLine maxN delta ix = min (max 0 (ix + delta)) maxN
539+-- | Low-level widget combinator that runs a child widget within
672− lineIndex :: Dynamic t Int <- foldDyn (\(maxN, delta) ix -> updateLine (maxN - 1) delta ix) 0 $
540+-- a given region and context. This widget filters and modifies the input
673− attach (length <$> imgs) requestedScroll
541+-- that the child widget receives such that:
674− tellImages $ fmap ((:[]) . V.vertCat) $ drop <$> current lineIndex <*> imgs
542+-- * unfocused widgets receive no key events
675− return $ (,) <$> ((+) <$> current lineIndex <*> pure 1) <*> (length <$> imgs)
543+-- * mouse inputs outside the region are ignored
676− where
544+-- * mouse inputs inside the region have their coordinates translated such
677− wrap maxWidth = concatMap (fmap (V.string V.defAttr . T.unpack) . TZ.wrapWithOffset maxWidth 0) . T.split (=='\n')
545+-- that (0,0) is the top-left corner of the region
547+ :: (Reflex t, Monad m, HasInput t m, HasImageWriter t m, HasDisplayRegion t m, HasFocusReader t m)
549+ -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
552+pane dr foc child = localRegion (const dr) $
553+ mapImages (imagesInRegion $ current dr) $
554+ localFocus (const foc) $
555+ inputInFocusedRegion >>= \e -> localInput (const e) child
679−-- | Renders any behavior whose value can be converted to
557+-- * Misc
682− :: (Reflex t, Monad m, Show a)
685−display a = text $ T.pack . show <$> a
687-- | A widget that draws nothing
559-- | A widget that draws nothing
688−blank :: Monad m => VtyWidget t m ()
560+blank :: Monad m => m ()
689blank = return ()
561blank = return ()