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Counter.hs
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Counter.hs
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{-----------------------------------------------------------------------------
reactive-banana-wx
Example: Counter
------------------------------------------------------------------------------}
{-# LANGUAGE ScopedTypeVariables #-}
-- allows pattern signatures like
-- do
-- (b :: Behavior Int) <- stepper 0 ...
import Graphics.UI.WX hiding (Event)
import Reactive.Banana
import Reactive.Banana.WX
{-----------------------------------------------------------------------------
Main
------------------------------------------------------------------------------}
main :: IO ()
main = start $ do
f <- frame [text := "Counter"]
bup <- button f [text := "Up"]
bdown <- button f [text := "Down"]
output <- staticText f []
set f [layout := margin 10 $
column 5 [widget bup, widget bdown, widget output]]
let networkDescription :: MomentIO ()
networkDescription = do
eup <- event0 bup command
edown <- event0 bdown command
(counter :: Behavior Int)
<- accumB 0 $ unions
[ (+1) <$ eup
, subtract 1 <$ edown
]
sink output [text :== show <$> counter]
network <- compile networkDescription
actuate network