In questo caso si vorrebbe effettivamente utilizzare purescript-aff-coroutines
. Che vi porterà un coroutine Producer
che è quindi possibile collegare a un Consumer
che spinge i messaggi nel driver:
module Main where
import Prelude
import Control.Coroutine (Producer, Consumer, consumer, runProcess, ($$))
import Control.Coroutine.Aff (produce)
import Control.Monad.Aff (Aff)
import Control.Monad.Aff.AVar (AVAR)
import Control.Monad.Eff (Eff)
import Control.Monad.Eff.Exception (EXCEPTION)
import Control.Monad.Eff.Var (($=))
import Data.Array as Array
import Data.Either (Either(..))
import Data.Maybe (Maybe(..))
import Halogen as H
import Halogen.HTML.Indexed as HH
import Halogen.Util (runHalogenAff, awaitBody)
import WebSocket (WEBSOCKET, Connection(..), Message(..), URL(..), runMessageEvent, runMessage, newWebSocket)
----------------------------------------------------------------------------
-- Halogen component. This just displays a list of messages and has a query
-- to accept new messages.
----------------------------------------------------------------------------
type State = { messages :: Array String }
initialState :: State
initialState = { messages: [] }
data Query a = AddMessage String a
ui :: forall g. H.Component State Query g
ui = H.component { render, eval }
where
render :: State -> H.ComponentHTML Query
render state =
HH.ol_ $ map (\msg -> HH.li_ [ HH.text msg ]) state.messages
eval :: Query ~> H.ComponentDSL State Query g
eval (AddMessage msg next) = do
H.modify \st -> { messages: st.messages `Array.snoc` msg }
pure next
----------------------------------------------------------------------------
-- Websocket coroutine producer. This uses `purescript-aff-coroutines` to
-- create a producer of messages from a websocket.
----------------------------------------------------------------------------
wsProducer :: forall eff. Producer String (Aff (avar :: AVAR, err :: EXCEPTION, ws :: WEBSOCKET | eff)) Unit
wsProducer = produce \emit -> do
Connection socket <- newWebSocket (URL "ws://echo.websocket.org") []
-- This part is probably unnecessary in the real world, but it gives us
-- some messages to consume when using the echo service
socket.onopen $= \event -> do
socket.send (Message "hello")
socket.send (Message "something")
socket.send (Message "goodbye")
socket.onmessage $= \event -> do
emit $ Left $ runMessage (runMessageEvent event)
----------------------------------------------------------------------------
-- Coroutine consumer. This accepts a Halogen driver function and sends
-- `AddMessage` queries in when the coroutine consumes an input.
----------------------------------------------------------------------------
wsConsumer
:: forall eff
. (Query ~> Aff (H.HalogenEffects (ws :: WEBSOCKET | eff)))
-> Consumer String (Aff (H.HalogenEffects (ws :: WEBSOCKET | eff))) Unit
wsConsumer driver = consumer \msg -> do
driver $ H.action $ AddMessage msg
pure Nothing
----------------------------------------------------------------------------
-- Normal Halogen-style `main`, the only addition is a use of `runProcess`
-- to connect the producer and consumer and start sending messages to the
-- Halogen component.
----------------------------------------------------------------------------
main :: forall eff. Eff (H.HalogenEffects (ws :: WEBSOCKET | eff)) Unit
main = runHalogenAff do
body <- awaitBody
driver <- H.runUI ui initialState body
runProcess (wsProducer $$ wsConsumer driver)
pure unit
Questo dovrebbe dare una pagina che consente di stampare quasi subito:
- ciao
- qualcosa
- addio
Ma che sta facendo sempre Tutto ciò di cui hai bisogno, onesto! Se utilizzi il produttore con una fonte "reale" otterrai qualcosa di più simile a quello che ti serve.
fonte
2016-07-14 12:29:24