使用反应性香蕉中的数据设置自定义事件

Question

我有一个样本，我从reactive-banana回购。它使用gloss。但是当我处理事件时，我有自己的事件和数据。这些事件不一定是UI事件。所以我希望玻璃钢能帮助我对定制事件进行编码。因此，例如，列表可能会更改，更改后的数据在事件中，应用程序的另一部分使用更改的数据。我的初步Haskell知识并没有帮助我使用reactive-banana实现这一目标，但我确实遇到了类似的东西。

我如何使用我自己的事件，如makeTickEvent，并解雇他们？它能保存数据吗？

{-# LANGUAGE ScopedTypeVariables #-}

module Main where
import Control.Monad (when)
import Data.Maybe (isJust, fromJust)
import Data.List (nub)
import System.Random
import System.IO
import Debug.Trace
import Data.IORef
import Reactive.Banana as R
import Reactive.Banana.Frameworks as R

import Graphics.Gloss
import Graphics.Gloss.Data.Extent
import Graphics.Gloss.Interface.Pure.Game
import Graphics.Gloss.Data.Picture

main :: IO()
main = do
    sources <- makeSources
    network <- compile $ networkDescription sources
    actuate network
    eventLoop sources
    display windowDisplay white drawBoard

windowDisplay :: Display
windowDisplay = InWindow "Window" (200, 200) (10, 10)

makeTickEvent :: MomentIO (R.Event ())
makeTickEvent = do
  (etick, tick) <- newEvent
  
  tid <- liftIO  $ do
    tick ()

  pure etick

drawBoard :: Picture
drawBoard =
  Pictures $ [ translate x y $ rectangleWire 90 90| x<-[0,90..180], y<-[0,90..180] ] 


makeSources =  newAddHandler


type EventSource a = (AddHandler a, a -> IO ())



addHandler :: EventSource a -> AddHandler a
addHandler = fst

eventLoop :: (EventSource ())  -> IO ()
eventLoop (displayvalueevent)  =
  fire displayvalueevent ()

fire :: EventSource a -> a -> IO ()
fire = snd


networkDescription :: (EventSource ()) -> MomentIO ()
networkDescription ( displayvalueevent )= do
  -- Obtain events 
  displayvalue <- fromAddHandler (addHandler displayvalueevent)
  reactimate $ putStrLn . showValue <$> displayvalue
 
showValue value = "Value is " ++ show value

这是文件里的。

plainChanges :: Behavior a -> MomentIO (Event a)
plainChanges b = do
    (e, handle) <- newEvent
    eb <- changes b
    reactimate' $ (fmap handle) <$> eb
    return e

这是否会创建一个可以触发的新事件？

Answer 1

目前，我已经设法使此代码正常工作了。一个事件被触发，一个新的框架呈现在初始的光泽窗口中。似乎有可能触发自定义事件。但我不确定是否将数据封装在事件中。

makeNewEvent :: MomentIO (Reactive.Banana.Event ())
makeNewEvent = do
  (enew, new) <- newEvent
  
  tid <- liftIO  $ do
    putStrLn "Fire new Event" 
    new ()

  return enew 

下面的代码回答了一些问题。如果我有更多的细节，我可以稍后编辑。这仍然是非常基本的，因为我正在学习reactive-banana和haskell

------------------------------------------------------------------------------}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE BlockArguments #-}

module Main where
import Data.IORef
import Data.Bool (bool)
import Data.IORef (newIORef, readIORef, writeIORef)
import Graphics.Gloss hiding (pictures)
import Reactive.Banana
import Reactive.Banana.Frameworks
import Graphics.Gloss.Interface.IO.Game( Event(..) )
import Graphics.Gloss.Interface.IO.Game( MouseButton(..) )
import Graphics.Gloss.Interface.IO.Game( KeyState( Down ) )
import Graphics.Gloss.Interface.IO.Game
import qualified Graphics.Gloss.Interface.IO.Game as Gloss (Event, playIO)


main = do

   (eventHandler,event)<- makeSources
   picRef ← newIORef blank
  
   network <- compile $ networkDescriptor picRef eventHandler
   actuate network
   let handleEvent e@(EventKey k Down _ _) = case k of
            (SpecialKey KeySpace) -> event e
            _                   -> return ()
       handleEvent e = return ()

   Gloss.playIO
    (InWindow "Functional Reactive" (550, 490) (800, 200))
    white
    30
    ()
    (\() -> readIORef picRef)
    (\ ev () -> handleEvent ev)
    (\_ () -> pure ())

reactToKeyPress :: IO ()
reactToKeyPress = putStrLn "Key Pressed"

drawBoard :: Picture
drawBoard =
   Pictures $ [ color violet $ translate x y $ rectangleWire 90 90| x<-[0,90..180], y<-[0,90..180] ] 

makeSources =  newAddHandler

type EventSource a = (AddHandler a, a -> IO ())

addHandler :: EventSource a -> AddHandler a
addHandler = fst

fire :: EventSource a -> a -> IO ()
fire = snd

networkDescriptor :: IORef Picture -> AddHandler Gloss.Event -> MomentIO ()
networkDescriptor lastFrame  displayGlossEvent = do
  glossEvent <- fromAddHandler displayGlossEvent
  reactimate $ putStrLn . showValue <$> glossEvent

  picture <- liftMoment (handleKeys glossEvent )
  changes picture >>= reactimate' . fmap (fmap (writeIORef lastFrame))
  valueBLater picture >>= liftIO . writeIORef lastFrame

showValue value = "Value is " ++ show value

handleKeys :: Reactive.Banana.Event e  -> Moment (Behavior Picture)
handleKeys glossEvent = do

  let picture = drawBoard
  return $ pure picture