Using websockets with scotty haskell

client.js

function webSocketTest()
{
  var ws = new WebSocket("ws://localhost:80");
	
  ws.onopen = () => {
    ws.send("initial from js");
  };
  
  ws.onmessage = evt => { 
    var m = evt.data;
    console.log( m );
  };
  
  ws.onclose = function() { 
    alert("ws closed"); 
  };
		
  window.onbeforeunload = evt => {
    socket.close();
  };
}

Scotty_websockets.hs

{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE OverloadedStrings #-}

module Main where

import Protolude 
import qualified Web.Scotty as Sc
import qualified Data.Text as Txt
import qualified Network.Wai.Middleware.Gzip as Sc
import qualified Network.Wai.Handler.WebSockets as WaiWs
import qualified Network.WebSockets as WS
import qualified Network.Wai as Wai
import qualified Network.Wai.Handler.Warp as Warp

main :: IO ()
main = do
  let port = 80
  let settings = Warp.setPort port Warp.defaultSettings
  sapp <- scottyApp
  Warp.runSettings settings $ WaiWs.websocketsOr WS.defaultConnectionOptions wsapp sapp

scottyApp :: IO Wai.Application
scottyApp = 
  Sc.scottyApp $ do
    Sc.middleware $ Sc.gzip $ Sc.def { Sc.gzipFiles = Sc.GzipCompress }
    --Sc.middleware S.logStdoutDev

    Sc.get "/" $
      Sc.file "index.html"

wsapp :: WS.ServerApp
wsapp pending = do
  putText "ws connected"
  conn <- WS.acceptRequest pending
  WS.forkPingThread conn 30

  (msg :: Text) <- WS.receiveData conn
  WS.sendTextData conn $ ("initial> " :: Text) <> msg

  forever $ do
    WS.sendTextData conn $ ("loop data" :: Text)
    threadDelay $ 1 * 1000000

Thanks a lot for this

Exactly the minimal example I was looking for.
Thanks!

very helpful, thanks!

https://gist.github.com/andrevdm/9560b5e31933391694811bf22e25c312#file-scotty_websockets-hs-L42 is causing trouble for me.

This could be fixed by adding Text annotation: WS.sendTextData conn $ ("loop data" :: Text)

Thanks @modotte, I've updated.

I'm reasonably sure it worked before, but it has been a while :)