loop.purs

module TestTime where

import Prelude
import Thermite as T
import Control.Monad.Aff (later')
import Control.Monad.Eff.Class (liftEff)
import Control.Monad.Eff.Console (log, CONSOLE)
import Control.Monad.Eff.Now (NOW, nowDateTime)
import Control.Monad.Maybe.Trans (runMaybeT)
import Control.Monad.Rec.Class (forever)
import Control.Monad.Trans (lift)
import Data.Maybe (Maybe(..))

data GameAction = Tick
type Effect eff = ( console :: CONSOLE, now :: NOW | eff )
type GameState = { t :: Int }

perform1 :: forall eff props. T.PerformAction (Effect eff) GameState props GameAction
perform1 Tick _ _ = forever do
  _ <- lift $ later' 1000 (pure unit)
  now <- lift $ liftEff $ nowDateTime
  lift $ liftEff $ log "tick!"
  void $ T.cotransform (\s -> s { t = s.t + 1 })

-- adding runMaybeT

perform2 :: forall eff props. T.PerformAction (Effect eff) GameState props GameAction
perform2 Tick _ _ = void $ runMaybeT $ forever do
  _ <- lift $ lift $ later' 1000 (pure unit)
  now <- lift $ lift $ liftEff $ nowDateTime
  lift $ (T.cotransform (\s -> s { t = s.t + 1 }))
  pure Nothing

  -- ^ that last line does not seem to stop the loop!