purescript-choco-pie

A Cycle.js-like utility for working with Purescript-Event. Aptly named for a circular Korean snack food.

Usage

program = runChocoPie main' drivers
  where
    main' ::
      { a :: Event Int
      , b :: Unit
      } ->
      { a :: Event Unit
      , b :: Event Int
      }
    main' sources =
      { a: mempty
      , b: sources.a
      }

    drivers ::
      { a :: Event Unit -> Eff _ (Event Int)
      , b :: Event Int -> Eff _ Unit
      }
    drivers =
      { a: const $ pure (pure 1)
      , b: \events -> subscribe events logShow
      }

With appropriate context and individual annotations, the type signature annotations are no longer needed.

Usage Exmples

I rewrote some code in my simple-rpc-telegram-bot repo, where I have drivers for running a child process, receiving and sending messages from Telegram, and a timer that ticks for every hour.

type Main
   = { torscraper :: Event Result
     , bot :: Event Request
     , timer :: Event Request
     }
  -> { torscraper :: Event Request
     , bot :: Event Result
     , timer :: Event Unit
     }
main' :: Main
main' sources =
  { torscraper: sources.timer <|> sources.bot
  , bot: sources.torscraper
  , timer: mempty
  }

drivers
  :: Config
  -> { torscraper :: Event Request -> Effect (Event Result)
     , bot :: Event Result -> Effect (Event Request)
     , timer :: Event Unit -> Effect (Event Request)
     }
drivers
  { token
  , torscraperPath
  , master
  } =
  { torscraper
  , bot
  , timer
  }
  where
    torscraper requests = do
      { event, push } <- create
      _ <- subscribe requests $ handleTorscraper torscraperPath master push
      pure event

    bot results = do
      connection <- connect $ unwrap token
      _ <- subscribe results $ sendMessage' connection
      messages <- getMessages connection
      pure $ { origin: FromUser, id: master } <$ messages

    timer _
      | tick <- pure unit <|> unit <$ interval (60 * 60 * 1000)
      , reqs <- { origin: FromTimer, id: master } <$ tick
      = pure reqs

-- runChocoPie main' (drivers config)

I also have a simpler example in atarime-purescript for similar usage of this library.