@@ -2,41 +2,160 @@
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 #-}
5−{-# Language UndecidableInstances #-}
18+{-# LANGUAGE UndecidableInstances #-}
7−module Reflex.Vty.Widget where
20+module Reflex.Vty.Widget
27+ , mainWidgetWithHandle
42+ , ScrollDirection(..)
9import Control.Applicative (liftA2)
71import Control.Applicative (liftA2)
10import Control.Monad.Fix (MonadFix)
72import Control.Monad.Fix (MonadFix)
11−import Control.Monad.IO.Class (MonadIO)
73+import Control.Monad.Reader
12−import Control.Monad.Morph
13−import Control.Monad.NodeId
14−import Control.Monad.Reader (ReaderT, ask, local, runReaderT)
15−import Control.Monad.Ref
16−import Control.Monad.Trans (MonadTrans, lift)
74+import Control.Monad.Trans (lift)
75+import Data.Default (Default(..))
17import Data.Set (Set)
76import Data.Set (Set)
18import qualified Data.Set as Set
77import qualified Data.Set as Set
78+import Data.Text (Text)
79+import qualified Data.Text as T
80+import qualified Data.Text.Zipper as TZ
19import Graphics.Vty (Image)
81import Graphics.Vty (Image)
20import qualified Graphics.Vty as V
82import qualified Graphics.Vty as V
21import Reflex
83import Reflex
22import Reflex.Class ()
84import Reflex.Class ()
23import Reflex.Host.Class (MonadReflexCreateTrigger)
85import Reflex.Host.Class (MonadReflexCreateTrigger)
24import Reflex.Vty.Host
87import Reflex.Vty.Host
26−-- * Running a vty application
89+import Control.Monad.NodeId
91+-- | The context within which a 'VtyWidget' runs
92+data VtyWidgetCtx t = VtyWidgetCtx
93+ { _vtyWidgetCtx_width :: Dynamic t Int
94+ -- ^ The width of the region allocated to the widget.
95+ , _vtyWidgetCtx_height :: Dynamic t Int
96+ -- ^ The height of the region allocated to the widget.
97+ , _vtyWidgetCtx_focus :: Dynamic t Bool
98+ -- ^ Whether the widget should behave as if it has focus for keyboard input.
99+ , _vtyWidgetCtx_input :: Event t VtyEvent
100+ -- ^ User input events that the widget's parent chooses to share. These will generally
101+ -- be filtered for relevance:
102+ -- * Keyboard inputs are restricted to focused widgets
103+ -- * Mouse inputs are restricted to the region in which the widget resides and are
104+ -- translated into its internal coordinates.
107+-- | The output of a 'VtyWidget'
108+data VtyWidgetOut t = VtyWidgetOut
109+ { _vtyWidgetOut_shutdown :: Event t ()
112+instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (VtyWidget t m) where
113+ runWithReplace a0 a' = VtyWidget $ runWithReplace (unVtyWidget a0) $ fmap unVtyWidget a'
114+ traverseIntMapWithKeyWithAdjust f dm0 dm' = VtyWidget $
115+ traverseIntMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
116+ traverseDMapWithKeyWithAdjust f dm0 dm' = VtyWidget $ do
117+ traverseDMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
118+ traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = VtyWidget $ do
119+ traverseDMapWithKeyWithAdjustWithMove (\k v -> unVtyWidget (f k v)) dm0 dm'
121+-- | A widget that can read its context and produce image output
122+newtype VtyWidget t m a = VtyWidget
123+ { unVtyWidget :: BehaviorWriterT t [Image] (ReaderT (VtyWidgetCtx t) m) a
135+ , MonadReflexCreateTrigger t
139+deriving instance PerformEvent t m => PerformEvent t (VtyWidget t m)
140+instance MonadTrans (VtyWidget t) where
141+ lift f = VtyWidget $ lift $ lift f
143+instance MonadNodeId m => MonadNodeId (VtyWidget t m) where
144+ getNextNodeId = VtyWidget $ do
145+ lift $ lift $ getNextNodeId
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
28−-- | Sets up the top-level context for a vty widget and runs it with that context
155+-- | Sets up the top-level context for a 'VtyWidget' and runs it with that context
29mainWidgetWithHandle
156mainWidgetWithHandle
32− ( MonadVtyApp t m
158+ -> (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
35− , HasDisplayRegion t m
41mainWidgetWithHandle vty child =
160mainWidgetWithHandle vty child =
42 runVtyAppWithHandle vty $ \dr0 inp -> do
161 runVtyAppWithHandle vty $ \dr0 inp -> do
@@ -46,178 +165,71 @@ mainWidgetWithHandle vty child =
46 let inp' = fforMaybe inp $ \case
165 let inp' = fforMaybe inp $ \case
47 V.EvResize {} -> Nothing
166 V.EvResize {} -> Nothing
48 x -> Just x
167 x -> Just x
49− (shutdown, images) <- runThemeReader (constant V.defAttr) $
168+ let ctx = VtyWidgetCtx
50− runFocusReader (pure True) $
169+ { _vtyWidgetCtx_width = fmap fst size
51− runDisplayRegion (fmap (\(w, h) -> Region 0 0 w h) size) $
170+ , _vtyWidgetCtx_height = fmap snd size
52− runImageWriter $
171+ , _vtyWidgetCtx_input = inp'
53− runNodeIdT $
172+ , _vtyWidgetCtx_focus = constDyn True
54− runInput inp' $ do
173+ }
174+ (shutdown, images) <- runNodeIdT $ runVtyWidget ctx $ do
55− tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
175+ tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
57 return $ VtyResult
177 return $ VtyResult
58 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
178 { _vtyResult_picture = fmap (V.picForLayers . reverse) images
59 , _vtyResult_shutdown = shutdown
179 , _vtyResult_shutdown = shutdown
62−-- | The output of a vty widget
63−data VtyWidgetOut t = VtyWidgetOut
64− { _vtyWidgetOut_shutdown :: Event t ()
67-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
182-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
68mainWidget
183mainWidget
70− ( MonadVtyApp t m
184+ :: (forall t m. (MonadVtyApp t m, MonadNodeId m) => VtyWidget t m (Event t ()))
73− , HasDisplayRegion t m
79mainWidget child = do
186mainWidget child = do
80 vty <- getDefaultVty
187 vty <- getDefaultVty
81 mainWidgetWithHandle vty child
188 mainWidgetWithHandle vty child
83−-- * Input Events
190+-- | A class for things that know their own display size dimensions
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)
85-- | A class for things that can receive vty events as input
212-- | A class for things that can receive vty events as input
86−class HasInput t m | m -> t where
213+class HasVtyInput t m | m -> t where
87 input :: m (Event t VtyEvent)
214 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
114−instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (Input t m) where
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
150−-- | Type synonym for a key and modifier combination
216+instance (Reflex t, Monad m) => HasVtyInput t (VtyWidget t m) where
151−type KeyCombo = (V.Key, [V.Modifier])
217+ input = VtyWidget . lift $ asks _vtyWidgetCtx_input
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)
219+-- | A class for things that can dynamically gain and lose focus
158−keys :: (Monad m, Reflex t, HasInput t m) => [V.Key] -> m (Event t KeyCombo)
220+class HasFocus t m | m -> t where
159−keys = keyCombos . Set.fromList . fmap (,[])
221+ focus :: m (Dynamic t Bool)
161−-- | Emit an event that fires whenever the provided key combination occurs
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
223+instance (Reflex t, Monad m) => HasFocus t (VtyWidget t m) where
169−keyCombos
224+ focus = VtyWidget . lift $ asks _vtyWidgetCtx_focus
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
226+-- | A class for widgets that can produce images to draw to the display
182−filterKeys :: (Reflex t, HasInput t m) => (KeyCombo -> Bool) -> m a -> m a
227+class (Reflex t, Monad m) => ImageWriter t m | m -> t where
183−filterKeys f x = localInput (ffilter (\case
228+ -- | Send images upstream for rendering
184− V.EvKey k mods -> f (k, mods)
229+ tellImages :: Behavior t [Image] -> m ()
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
231+instance (Monad m, Reflex t) => ImageWriter t (BehaviorWriterT t [Image] m) where
232+ tellImages = tellBehavior
222-- | A chunk of the display area
234-- | A chunk of the display area
223data Region = Region
235data Region = Region
@@ -228,334 +240,470 @@ data Region = Region
229 deriving (Show, Read, Eq, Ord)
241 deriving (Show, Read, Eq, Ord)
231−-- | A region that occupies no space.
243+-- | A dynamic chunk of the display area
232−nilRegion :: Region
244+data DynRegion t = DynRegion
233−nilRegion = Region 0 0 0 0
245+ { _dynRegion_left :: Dynamic t Int
246+ , _dynRegion_top :: Dynamic t Int
247+ , _dynRegion_width :: Dynamic t Int
248+ , _dynRegion_height :: Dynamic t Int
235-- | The width and height of a 'Region'
251-- | The width and height of a 'Region'
236regionSize :: Region -> (Int, Int)
252regionSize :: Region -> (Int, Int)
237regionSize (Region _ _ w h) = (w, h)
253regionSize (Region _ _ w h) = (w, h)
239-- | Produces an 'Image' that fills a region with space characters
255-- | Produces an 'Image' that fills a region with space characters
240−regionBlankImage :: V.Attr -> Region -> Image
256+regionBlankImage :: Region -> Image
241−regionBlankImage attr r@(Region _ _ width height) =
257+regionBlankImage r@(Region _ _ width height) =
242− withinImage r $ V.charFill attr ' ' width height
258+ withinImage r $ V.charFill V.defAttr ' ' width height
244−-- | A class for things that know their own display size dimensions
260+-- | A behavior of the current display area represented by a 'DynRegion'
245−class (Reflex t, Monad m) => HasDisplayRegion t m | m -> t where
261+currentRegion :: Reflex t => DynRegion t -> Behavior t Region
246− -- | Retrieve the display region
262+currentRegion (DynRegion l t w h) = Region <$> current l <*> current t <*> current w <*> current h
247− askRegion :: m (Dynamic t Region)
248− default askRegion :: (f m' ~ m, MonadTrans f, HasDisplayRegion t m') => m (Dynamic t Region)
249− askRegion = lift askRegion
250− -- | Run an action in a local region, by applying a transformation to the region
251− localRegion :: (Dynamic t Region -> Dynamic t Region) -> m a -> m a
252− default localRegion :: (f m' ~ m, Monad m', MFunctor f, HasDisplayRegion t m') => (Dynamic t Region -> Dynamic t Region) -> m a -> m a
253− localRegion f = hoist (localRegion f)
255−-- | Retrieve the display width
256−displayWidth :: HasDisplayRegion t m => m (Dynamic t Int)
257−displayWidth = fmap _region_width <$> 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)
264+-- | Translates and crops an 'Image' so that it is contained by
265+-- the given 'Region'.
270+withinImage (Region left top width height)
271+ | width < 0 || height < 0 = withinImage (Region left top 0 0)
272+ | otherwise = V.translate left top . V.crop width height
309−-- | Run a 'DisplayRegion' action with a given 'Region'
274+-- | Low-level widget combinator that runs a child 'VtyWidget' within
310−runDisplayRegion
275+-- a given region and context. This widget filters and modifies the input
276+-- that the child widget receives such that:
277+-- * unfocused widgets receive no key events
278+-- * mouse inputs outside the region are ignored
279+-- * mouse inputs inside the region have their coordinates translated such
280+-- that (0,0) is the top-left corner of the region
282+ :: (Reflex t, Monad m, MonadNodeId m)
284+ -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
287+pane dr foc child = VtyWidget $ do
289+ let reg = currentRegion dr
290+ let ctx' = VtyWidgetCtx
291+ { _vtyWidgetCtx_input = leftmost -- TODO: think about this leftmost more.
293+ attachWith (\(r,f) e -> filterInput r f e)
294+ (liftA2 (,) reg (current foc))
295+ (_vtyWidgetCtx_input ctx)
297+ , _vtyWidgetCtx_focus = liftA2 (&&) (_vtyWidgetCtx_focus ctx) foc
298+ , _vtyWidgetCtx_width = _dynRegion_width dr
299+ , _vtyWidgetCtx_height = _dynRegion_height dr
301+ (result, images) <- lift . lift $ runVtyWidget ctx' child
302+ let images' = liftA2 (\r is -> map (withinImage r) is) reg images
306+ filterInput :: Region -> Bool -> VtyEvent -> Maybe VtyEvent
307+ filterInput (Region l t w h) focused e = case e of
308+ V.EvKey _ _ | not focused -> Nothing
309+ V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
310+ V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
317+ , y >= t + h ] = Nothing
319+ Just (con (x - l) (y - t))
321+-- | Information about a drag operation
323+ { _drag_from :: (Int, Int) -- ^ Where the drag began
324+ , _drag_to :: (Int, Int) -- ^ Where the mouse currently is
325+ , _drag_button :: V.Button -- ^ Which mouse button is dragging
326+ , _drag_modifiers :: [V.Modifier] -- ^ What modifiers are held
327+ , _drag_end :: Bool -- ^ Whether the drag ended (the mouse button was released)
329+ deriving (Eq, Ord, Show)
331+-- | Converts raw vty mouse drag events into an event stream of 'Drag's
333+ :: (Reflex t, MonadFix m, MonadHold t m)
335+ -> VtyWidget t m (Event t Drag)
338+ let f :: Maybe Drag -> V.Event -> Maybe Drag
340+ V.EvMouseDown x y btn' mods
341+ | btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods False
342+ | otherwise -> Nothing
344+ f (Just (Drag from _ _ mods end)) = \case
345+ V.EvMouseDown x y btn' mods'
346+ | end && btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods' False
347+ | btn == btn' -> Just $ Drag from (x,y) btn mods' False
348+ | otherwise -> Nothing -- Ignore other buttons.
349+ V.EvMouseUp x y (Just btn')
351+ | btn == btn' -> Just $ Drag from (x,y) btn mods True
352+ | otherwise -> Nothing
353+ V.EvMouseUp x y Nothing -- Terminal doesn't specify mouse up button,
354+ -- assume it's the right one.
356+ | otherwise -> Just $ Drag from (x,y) btn mods True
358+ rec let newDrag = attachWithMaybe f (current dragD) inp
359+ dragD <- holdDyn Nothing $ Just <$> newDrag
360+ return (fmapMaybe id $ updated dragD)
362+-- | Mouse down events for a particular mouse button
311 :: (Reflex t, Monad m)
364 :: (Reflex t, Monad m)
312− => Dynamic t Region
365+ => V.Button
313− -> DisplayRegion t m a
366+ -> VtyWidget t m (Event t MouseDown)
314− -> m a
367+mouseDown btn = do
315−runDisplayRegion r = flip runReaderT r . unDisplayRegion
368+ i <- input
316−
369+ return $ fforMaybe i $ \case
317−-- * Getting focus state
370+ V.EvMouseDown x y btn' mods -> if btn == btn'
318−
371+ then Just $ MouseDown btn' (x, y) mods
319−-- | A class for things that can dynamically gain and lose focus
372+ else Nothing
320−class (Reflex t, Monad m) => HasFocusReader t m | m -> t where
373+ _ -> Nothing
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+-- | Mouse up events for a particular mouse button
374−runFocusReader
376+mouseUp
375 :: (Reflex t, Monad m)
377 :: (Reflex t, Monad m)
376− => Dynamic t Bool
378+ => VtyWidget t m (Event t MouseUp)
377− -> FocusReader t m a
379+mouseUp = do
378− -> m a
380+ i <- input
379−runFocusReader b = flip runReaderT b . unFocusReader
381+ return $ fforMaybe i $ \case
380−
382+ V.EvMouseUp x y btn' -> Just $ MouseUp btn' (x, y)
381−-- * "Image" output
383+ _ -> Nothing
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)
385+-- | Information about a mouse down event
426−instance HasImageWriter t m => HasImageWriter t (BehaviorWriterT t x m)
386+data MouseDown = MouseDown
427−instance HasImageWriter t m => HasImageWriter t (DynamicWriterT t x m)
387+ { _mouseDown_button :: V.Button
428−instance HasImageWriter t m => HasImageWriter t (EventWriterT t x m)
388+ , _mouseDown_coordinates :: (Int, Int)
429−instance HasImageWriter t m => HasImageWriter t (NodeIdT m)
389+ , _mouseDown_modifiers :: [V.Modifier]
391+ deriving (Eq, Ord, Show)
431−instance (Monad m, Reflex t) => HasImageWriter t (ImageWriter t m) where
393+-- | Information about a mouse up event
432− tellImages = ImageWriter . tellBehavior
394+data MouseUp = MouseUp
433− mapImages f (ImageWriter x) = ImageWriter $ do
395+ { _mouseUp_button :: Maybe V.Button
434− (a, images) <- lift $ runBehaviorWriterT x
396+ , _mouseUp_coordinates :: (Int, Int)
435− tellBehavior $ f images
397+ }
436− pure a
398+ deriving (Eq, Ord, Show)
438−instance HasDisplayRegion t m => HasDisplayRegion t (ImageWriter t m)
400+-- | Mouse scroll direction
439−instance HasFocusReader t m => HasFocusReader t (ImageWriter t m)
401+data ScrollDirection = ScrollDirection_Up | ScrollDirection_Down
402+ deriving (Eq, Ord, Show)
441−-- | Run a widget that can produce images
404+-- | Produce an event that fires when the mouse wheel is scrolled
442−runImageWriter
405+mouseScroll
443 :: (Reflex t, Monad m)
406 :: (Reflex t, Monad m)
444− => ImageWriter t m a
407+ => VtyWidget t m (Event t ScrollDirection)
445− -> m (a, Behavior t [Image])
408+mouseScroll = do
446−runImageWriter = runBehaviorWriterT . unImageWriter
409+ up <- mouseDown V.BScrollUp
447−
410+ down <- mouseDown V.BScrollDown
448−-- * Theming
411+ return $ leftmost
449−
412+ [ ScrollDirection_Up <$ up
450−-- | A class for things that can be visually styled
413+ , ScrollDirection_Down <$ down
451−class (Reflex t, Monad m) => HasTheme t m | m -> t where
414+ ]
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
416+-- | Type synonym for a key and modifier combination
501− lift = ThemeReader . lift
417+type KeyCombo = (V.Key, [V.Modifier])
503−instance MFunctor (ThemeReader t) where
419+-- | Emits an event that fires on a particular key press (without modifiers)
504− hoist f = ThemeReader . hoist f . unThemeReader
420+key :: (Monad m, Reflex t) => V.Key -> VtyWidget t m (Event t KeyCombo)
421+key = keyCombos . Set.singleton . (,[])
506−instance MonadNodeId m => MonadNodeId (ThemeReader t m)
423+-- | Emits an event that fires on particular key presses (without modifiers)
424+keys :: (Monad m, Reflex t) => [V.Key] -> VtyWidget t m (Event t KeyCombo)
425+keys = keyCombos . Set.fromList . fmap (,[])
508−-- | Run a 'ThemeReader' action with the given focus value
427+-- | Emit an event that fires whenever the provided key combination occurs
509−runThemeReader
428+keyCombo
510 :: (Reflex t, Monad m)
429 :: (Reflex t, Monad m)
511− => Behavior t V.Attr
430+ => KeyCombo
512− -> ThemeReader t m a
431+ -> VtyWidget t m (Event t KeyCombo)
513− -> m a
432+keyCombo = keyCombos . Set.singleton
514−runThemeReader b = flip runReaderT b . unThemeReader
434+-- | Emit an event that fires whenever any of the provided key combinations occur
436+ :: (Reflex t, Monad m)
438+ -> VtyWidget t m (Event t KeyCombo)
441+ return $ fforMaybe i $ \case
442+ V.EvKey k m -> if Set.member (k, m) ks
517−-- ** Manipulating images
447+-- | A plain split of the available space into vertically stacked panes.
448+-- No visual separator is built in here.
449+splitV :: (Reflex t, Monad m, MonadNodeId m)
450+ => Dynamic t (Int -> Int)
451+ -- ^ Function used to determine size of first pane based on available size
452+ -> Dynamic t (Bool, Bool)
453+ -- ^ How to focus the two sub-panes, given that we are focused.
455+ -- ^ Widget for first pane
457+ -- ^ Widget for second pane
458+ -> VtyWidget t m (a,b)
459+splitV sizeFunD focD wA wB = do
462+ let regA = DynRegion
463+ { _dynRegion_left = pure 0
464+ , _dynRegion_top = pure 0
465+ , _dynRegion_width = dw
466+ , _dynRegion_height = sizeFunD <*> dh
469+ { _dynRegion_left = pure 0
470+ , _dynRegion_top = _dynRegion_height regA
471+ , _dynRegion_width = dw
472+ , _dynRegion_height = liftA2 (-) dh (_dynRegion_height regA)
474+ ra <- pane regA (fst <$> focD) wA
475+ rb <- pane regB (snd <$> focD) wB
478+-- | A split of the available space into two parts with a draggable separator.
479+-- Starts with half the space allocated to each, and the first pane has focus.
480+-- Clicking in a pane switches focus.
481+splitVDrag :: (Reflex t, MonadFix m, MonadHold t m, MonadNodeId m)
485+ -> VtyWidget t m (a,b)
486+splitVDrag wS wA wB = do
489+ h0 <- sample $ current dh -- TODO
490+ dragE <- drag V.BLeft
491+ let splitter0 = h0 `div` 2
492+ rec splitterCheckpoint <- holdDyn splitter0 $ leftmost [fst <$> ffilter snd dragSplitter, resizeSplitter]
493+ splitterPos <- holdDyn splitter0 $ leftmost [fst <$> dragSplitter, resizeSplitter]
494+ splitterFrac <- holdDyn ((1::Double) / 2) $ ffor (attach (current dh) (fst <$> dragSplitter)) $ \(h, x) ->
495+ fromIntegral x / (max 1 (fromIntegral h))
496+ let dragSplitter = fforMaybe (attach (current splitterCheckpoint) dragE) $
497+ \(splitterY, Drag (_, fromY) (_, toY) _ _ end) ->
498+ if splitterY == fromY then Just (toY, end) else Nothing
499+ regA = DynRegion 0 0 dw splitterPos
500+ regS = DynRegion 0 splitterPos dw 1
501+ regB = DynRegion 0 (splitterPos + 1) dw (dh - splitterPos - 1)
502+ resizeSplitter = ffor (attach (current splitterFrac) (updated dh)) $
503+ \(frac, h) -> round (frac * fromIntegral h)
504+ focA <- holdDyn True $ leftmost
508+ (mA, rA) <- pane regA focA $ withMouseDown wA
509+ pane regS (pure False) wS
510+ (mB, rB) <- pane regB (not <$> focA) $ withMouseDown wB
513+ withMouseDown x = do
514+ m <- mouseDown V.BLeft
518+-- | Fill the background with a particular character.
519+fill :: (Reflex t, Monad m) => Char -> VtyWidget t m ()
523+ let fillImg = current $ liftA2 (\w h -> [V.charFill V.defAttr c w h]) dw dh
526+-- | Fill the background with the bottom
527+hRule :: (Reflex t, Monad m) => BoxStyle -> VtyWidget t m ()
528+hRule boxStyle = fill (_boxStyle_s boxStyle)
530+-- | Defines a set of symbols to use to draw the outlines of boxes
531+-- C.f. https://en.wikipedia.org/wiki/Box-drawing_character
532+data BoxStyle = BoxStyle
533+ { _boxStyle_nw :: Char
534+ , _boxStyle_n :: Char
535+ , _boxStyle_ne :: Char
536+ , _boxStyle_e :: Char
537+ , _boxStyle_se :: Char
538+ , _boxStyle_s :: Char
539+ , _boxStyle_sw :: Char
540+ , _boxStyle_w :: Char
519−-- | Translates and crops an 'Image' so that it is contained by
543+instance Default BoxStyle where
520−-- the given 'Region'.
544+ def = singleBoxStyle
522− :: Region
546+-- | A box style that uses hyphens and pipe characters. Doesn't handle
523− -> Image
547+-- corners very well.
524− -> Image
548+hyphenBoxStyle :: BoxStyle
525−withinImage (Region left top width height)
549+hyphenBoxStyle = BoxStyle '-' '-' '-' '|' '-' '-' '-' '|'
526− | width < 0 || height < 0 = withinImage (Region left top 0 0)
550+
527− | otherwise = V.translate left top . V.crop width height
551+-- | A single line box style
552+singleBoxStyle :: BoxStyle
553+singleBoxStyle = BoxStyle '┌' '─' '┐' '│' '┘' '─' '└' '│'
555+-- | A thick single line box style
556+thickBoxStyle :: BoxStyle
557+thickBoxStyle = BoxStyle '┏' '━' '┓' '┃' '┛' '━' '┗' '┃'
559+-- | A double line box style
560+doubleBoxStyle :: BoxStyle
561+doubleBoxStyle = BoxStyle '╔' '═' '╗' '║' '╝' '═' '╚' '║'
563+-- | A single line box style with rounded corners
564+roundedBoxStyle :: BoxStyle
565+roundedBoxStyle = BoxStyle '╭' '─' '╮' '│' '╯' '─' '╰' '│'
567+-- | Draws a titled box in the provided style and a child widget inside of that box
568+boxTitle :: (Monad m, Reflex t, MonadNodeId m)
569+ => Behavior t BoxStyle
573+boxTitle boxStyle title child = do
576+ let boxReg = DynRegion (pure 0) (pure 0) dw dh
577+ innerReg = DynRegion (pure 1) (pure 1) (subtract 2 <$> dw) (subtract 2 <$> dh)
578+ tellImages (boxImages <$> boxStyle <*> currentRegion boxReg)
579+ tellImages (fmap (\r -> [regionBlankImage r]) (currentRegion innerReg))
580+ pane innerReg (pure True) child
582+ boxImages :: BoxStyle -> Region -> [Image]
583+ boxImages style (Region left top width height) =
584+ let right = left + width - 1
585+ bottom = top + height - 1
587+ [ withinImage (Region (left + 1) top (width - 2) 1) $
589+ hPadText title (_boxStyle_n style) (width - 2)
590+ , withinImage (Region right (top + 1) 1 (height - 2)) $
591+ V.charFill V.defAttr (_boxStyle_e style) 1 (height - 2)
592+ , withinImage (Region (left + 1) bottom (width - 2) 1) $
593+ V.charFill V.defAttr (_boxStyle_s style) (width - 2) 1
594+ , withinImage (Region left (top + 1) 1 (height - 2)) $
595+ V.charFill V.defAttr (_boxStyle_w style) 1 (height - 2)
598+ [ withinImage (Region left top 1 1) $
599+ V.char V.defAttr (_boxStyle_nw style)
600+ , withinImage (Region right top 1 1) $
601+ V.char V.defAttr (_boxStyle_ne style)
602+ , withinImage (Region right bottom 1 1) $
603+ V.char V.defAttr (_boxStyle_se style)
604+ , withinImage (Region left bottom 1 1) $
605+ V.char V.defAttr (_boxStyle_sw style)
607+ in sides ++ if width > 1 && height > 1 then corners else []
608+ hPadText :: T.Text -> Char -> Int -> T.Text
609+ hPadText t c l = if lt >= l
611+ else left <> t <> right
615+ mkHalf n = T.replicate (n `div` 2) (T.singleton c)
616+ left = mkHalf $ delta + 1
617+ right = mkHalf delta
619+-- | A box without a title
620+box :: (Monad m, Reflex t, MonadNodeId m)
621+ => Behavior t BoxStyle
624+box boxStyle = boxTitle boxStyle mempty
626+-- | A box whose style is static
628+ :: (Reflex t, Monad m, MonadNodeId m)
632+boxStatic = box . pure
634+-- | Configuration options for displaying "rich" text
635+data RichTextConfig t = RichTextConfig
636+ { _richTextConfig_attributes :: Behavior t V.Attr
529−-- | Crop a behavior of images to a behavior of regions. See 'withinImage'.
639+instance Reflex t => Default (RichTextConfig t) where
530−imagesInRegion
640+ def = RichTextConfig $ pure V.defAttr
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
642+-- | A widget that displays text with custom time-varying attributes
644+ :: (Reflex t, Monad m)
650+ let img = (\w a s -> [wrapText w a s])
652+ <*> _richTextConfig_attributes cfg
656+ wrapText maxWidth attrs = V.vertCat
657+ . concatMap (fmap (V.string attrs . T.unpack) . TZ.wrapWithOffset maxWidth 0)
539−-- | Low-level widget combinator that runs a child widget within
660+-- | Renders text, wrapped to the container width
540−-- a given region and context. This widget filters and modifies the input
661+text
541−-- that the child widget receives such that:
662+ :: (Reflex t, Monad m)
542−-- * unfocused widgets receive no key events
663+ => Behavior t Text
543−-- * mouse inputs outside the region are ignored
664+ -> VtyWidget t m ()
544−-- * mouse inputs inside the region have their coordinates translated such
665+text = richText def
545−-- that (0,0) is the top-left corner of the region
666+
546−pane
667+-- | Scrollable text widget. The output pair exposes the current scroll position and total number of lines (including those
547− :: (Reflex t, Monad m, HasInput t m, HasImageWriter t m, HasDisplayRegion t m, HasFocusReader t m)
668+-- that are hidden)
548− => Dynamic t Region
669+scrollableText
549− -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
670+ :: forall t m. (Reflex t, MonadHold t m, MonadFix m)
550− -> m a
671+ => Event t Int
551− -> m a
672+ -- ^ Number of lines to scroll by
552−pane dr foc child = localRegion (const dr) $
673+ -> Behavior t Text
553− mapImages (imagesInRegion $ current dr) $
674+ -> VtyWidget t m (Behavior t (Int, Int))
554− localFocus (const foc) $
675+ -- ^ (Current scroll position, total number of lines)
555− inputInFocusedRegion >>= \e -> localInput (const e) child
676+scrollableText scrollBy t = do
678+ let imgs = wrap <$> current dw <*> t
680+ kdown <- key V.KDown
682+ let requestedScroll :: Event t Int
683+ requestedScroll = leftmost
687+ ScrollDirection_Up -> (-1)
688+ ScrollDirection_Down -> 1
691+ updateLine maxN delta ix = min (max 0 (ix + delta)) maxN
692+ lineIndex :: Dynamic t Int <- foldDyn (\(maxN, delta) ix -> updateLine (maxN - 1) delta ix) 0 $
693+ attach (length <$> imgs) requestedScroll
694+ tellImages $ fmap ((:[]) . V.vertCat) $ drop <$> current lineIndex <*> imgs
695+ return $ (,) <$> ((+) <$> current lineIndex <*> pure 1) <*> (length <$> imgs)
697+ wrap maxWidth = concatMap (fmap (V.string V.defAttr . T.unpack) . TZ.wrapWithOffset maxWidth 0) . T.split (=='\n')
557−-- * Misc
699+-- | Renders any behavior whose value can be converted to
702+ :: (Reflex t, Monad m, Show a)
705+display a = text $ T.pack . show <$> a
559-- | A widget that draws nothing
707-- | A widget that draws nothing
560−blank :: Monad m => m ()
708+blank :: Monad m => VtyWidget t m ()
561blank = return ()
709blank = return ()