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{-----------------------------------------------------------------------------
reactive-banana-wx
Example: Two Counters.
------------------------------------------------------------------------------}
{-# LANGUAGE ScopedTypeVariables #-}
-- allows pattern signatures like
-- do
-- (b :: Behavior Int) <- stepper 0 ...
{-# LANGUAGE RecursiveDo #-}
-- allows recursive do notation
-- mdo
-- ...
import Graphics.UI.WX hiding (Event)
import Reactive.Banana
import Reactive.Banana.WX
{-----------------------------------------------------------------------------
Main
------------------------------------------------------------------------------}
main :: IO ()
main = start $ do
f <- frame [text := "Two Counters"]
bup <- button f [text := "Up"]
bdown <- button f [text := "Down"]
bswitch <- button f [text := "Switch Counters"]
out1 <- staticText f []
out2 <- staticText f []
set f [layout := margin 10 $
column 5 [row 5 [widget bup, widget bdown, widget bswitch],
grid 5 5 [[label "First Counter:" , widget out1]
,[label "Second Counter:", widget out2]]]]
let networkDescription :: forall t. MomentIO ()
networkDescription = mdo
eup <- event0 bup command
edown <- event0 bdown command
eswitch <- event0 bswitch command
let
-- do we act on the left button?
(firstcounter :: Behavior Bool)
<- accumB True $ not <$ eswitch
-- joined state of the two counters
(counters :: Behavior (Int, Int))
<- accumB (0,0) $ unions
[ increment <$> firstcounter <@> eup
, decrement <$> firstcounter <@> edown
]
let
increment left _ (x,y) = if left then (x+1,y) else (x,y+1)
decrement left _ (x,y) = if left then (x-1,y) else (x,y-1)
sink out1 [text :== show . fst <$> counters]
sink out2 [text :== show . snd <$> counters]
network <- compile networkDescription
actuate network