PresentationExamples.hs

{-# LANGUAGE Arrows                #-}
{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies          #-}

-- dunai
import Data.MonadicStreamFunction

-- rhine
import FRP.Rhine
import FRP.Rhine.ClSF.Except
import FRP.Rhine.Clock.Realtime.Millisecond

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verboseSum :: MSF IO Int Int
verboseSum = proc n -> do
  s <- accumulateWith (+) 0 -< n
  _ <- arrM print -< "The sum is now " ++ show s
  returnA -< s


main1 = reactimate
  $   (arrM $ const $ putStrLn "Enter a number:" >> readLn)
  >>> verboseSum
  >>> arr (const ())

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type SumClock = Millisecond 100

fillUp :: Monad m => ClSF (ExceptT Double m) SumClock Double ()
fillUp = proc x -> do
  s <- integral -< x
  _ <- throwOn' -< (s > 5, s)
  returnA       -< ()

helloWorld :: ClSFExcept IO SumClock () () Empty
helloWorld = do
  try $ arr (const 1) >>> fillUp
  once_ $ putStrLn "Hello World!"
  helloWorld

main = flow $ safely helloWorld @@ waitClock

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data FastClock = FastClock
instance Clock m FastClock where
  type Time FastClock = ()
  type Tag          FastClock = ()
  initClock = undefined

data SlowClock = SlowClock
instance Clock m SlowClock where
  type Time SlowClock = ()
  type Tag          SlowClock = ()
  initClock = undefined

fastSignal :: ClSF m FastClock () a
fastSignal = undefined

slowProcessor :: ClSF m SlowClock b c
slowProcessor = undefined

-- uncomment the following for a clock type error
-- clockTypeError = fastSignal >>> slowProcessor

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-- rhmain = putStrLn "Uncomment one of the example mains in the file PresentationExamples.hs!"