brick/programs/CustomEventDemo.hs
Jonathan Daugherty bd89f787d2 Support GHC 8.4 (fixes #162)
This change splits up Monoid instances into Monoid and Semigroup. It
also conditionally imports Data.Monoid on GHCs prior to 8.4.
2018-03-17 09:03:59 -07:00

86 lines
1.9 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE CPP #-}
module Main where
import Lens.Micro ((^.), (&), (.~), (%~))
import Lens.Micro.TH (makeLenses)
import Control.Monad (void, forever)
import Control.Concurrent (threadDelay, forkIO)
#if !(MIN_VERSION_base(4,11,0))
import Data.Monoid
#endif
import qualified Graphics.Vty as V
import Brick.BChan
import Brick.Main
( App(..)
, showFirstCursor
, customMain
, continue
, halt
)
import Brick.AttrMap
( attrMap
)
import Brick.Types
( Widget
, Next
, EventM
, BrickEvent(..)
)
import Brick.Widgets.Core
( (<=>)
, str
)
data CustomEvent = Counter deriving Show
data St =
St { _stLastBrickEvent :: Maybe (BrickEvent () CustomEvent)
, _stCounter :: Int
}
makeLenses ''St
drawUI :: St -> [Widget ()]
drawUI st = [a]
where
a = (str $ "Last event: " <> (show $ st^.stLastBrickEvent))
<=>
(str $ "Counter value is: " <> (show $ st^.stCounter))
appEvent :: St -> BrickEvent () CustomEvent -> EventM () (Next St)
appEvent st e =
case e of
VtyEvent (V.EvKey V.KEsc []) -> halt st
VtyEvent _ -> continue $ st & stLastBrickEvent .~ (Just e)
AppEvent Counter -> continue $ st & stCounter %~ (+1)
& stLastBrickEvent .~ (Just e)
_ -> continue st
initialState :: St
initialState =
St { _stLastBrickEvent = Nothing
, _stCounter = 0
}
theApp :: App St CustomEvent ()
theApp =
App { appDraw = drawUI
, appChooseCursor = showFirstCursor
, appHandleEvent = appEvent
, appStartEvent = return
, appAttrMap = const $ attrMap V.defAttr []
}
main :: IO ()
main = do
chan <- newBChan 10
forkIO $ forever $ do
writeBChan chan Counter
threadDelay 1000000
void $ customMain (V.mkVty V.defaultConfig) (Just chan) theApp initialState