Main.hs

module Main where
  import Prelude hiding (until)
  -- import System.CPUTime

  -- 2.1 Semantic Domains
  type Time = Double
  type Behavior a = Time -> a
  type Event a = (Time, a)
  -- type Events a = [Event a]

  -- 2.2 Semantics of Behaviors
  -- Time
  time :: Behavior Time
  time = id

  -- Lifting
  lift0 :: a -> Behavior a
  lift0 value =
    \time ->
      value

  lift1 :: (a -> b) -> Behavior a -> Behavior b
  lift1 function behavior =
    \time ->
      function $ behavior time

  lift2 :: (a -> b -> c) -> Behavior a -> Behavior b -> Behavior c
  lift2 function behavior1 behavior2 =
    \time ->
      function (behavior1 time) (behavior2 time)

  lift3 :: (a -> b -> c -> d) -> Behavior a -> Behavior b -> Behavior c -> Behavior d
  lift3 function behavior1 behavior2 behavior3 =
    \time ->
      function (behavior1 time) (behavior2 time) (behavior3 time)

  -- Time Transformation
  timeTransform :: Behavior a -> Behavior Time -> Behavior a
  timeTransform behavior timeBehavior = behavior . timeBehavior

  -- Integration
  -- integral :: ...

  -- Reactivity
  until :: Behavior a -> Event (Behavior a) -> Behavior a
  until behavior event =
    \time ->
      if time < fst event then
        behavior time
      else
        snd event $ time

  -- Event Handlers
  (+=>) :: Event a -> (Time -> a -> b) -> Event b
  (+=>) (eventTime, eventValue) function =
    (eventTime, function eventTime eventValue)

  (==>) :: Event a -> (a -> b) -> Event b
  (==>) (eventTime, eventValue) function =
    (eventTime, function eventValue)

  (*=>) :: Event a -> (Time -> b) -> Event b
  (*=>) (eventTime, _) function =
    (eventTime, function eventTime)

  (-=>) :: Event a -> b -> Event b
  (-=>) (eventTime, _) value =
    (eventTime, value)

  -- Constant Events
  constEv :: Time -> a -> Event a
  constEv time value = (time, value)

  -- External Events
  -- ...

  -- Predicates
  -- predicate :: ...

  -- Choice
  -- (.|.) :: Event a -> Event a -> Event a
  -- (.|.) event1 event2 =

  -- now :: IO Time
  -- now = getCPUTime >>= return . fromIntegral

  main :: IO ()
  main = undefined