Add selector to init funciton using somewhat existentials (Thanks Hayleigh!!)

Author: renatillas

examples/src/working_with_websockets/app/router.gleam

@@ -1,4 +1,5 @@
 import gleam/int
+import gleam/option
 import wisp.{type Request, type Response}
 import wisp/websocket
 
@@ -114,7 +115,7 @@ fn home_page() -> Response {
 fn websocket_handler(request: Request) -> Response {
   wisp.websocket(
     request,
-    on_init: fn(_connection) { 0 },
+    on_init: fn(_connection) { #(0, option.None) },
     on_message: fn(state, message, connection) {
       case message {
         websocket.Text(text) -> {
@@ -133,6 +134,7 @@ fn websocket_handler(request: Request) -> Response {
         }
         websocket.Closed -> websocket.Stop
         websocket.Shutdown -> websocket.Stop
+        websocket.Custom(_) -> websocket.Stop
       }
     },
     on_close: fn(state) {

examples/test/working_with_websockets/app_test.gleam

@@ -30,7 +30,7 @@ pub fn websocket_text_echo_test() {
   let response = router.handle_request(request)
 
   let assert wisp.WebSocket(upgrade) = response.body
-  let handler = wisp.upgrade_to_websocket(upgrade)
+  let handler = wisp.recover(upgrade)
   let assert Ok(ws) = simulate.create_websocket(handler)
 
   // Send first text message
@@ -54,7 +54,7 @@ pub fn websocket_binary_echo_test() {
   let response = router.handle_request(request)
 
   let assert wisp.WebSocket(upgrade) = response.body
-  let handler = wisp.upgrade_to_websocket(upgrade)
+  let handler = wisp.recover(upgrade)
   let assert Ok(ws) = simulate.create_websocket(handler)
 
   // Send binary message
@@ -73,7 +73,7 @@ pub fn websocket_mixed_messages_test() {
   let response = router.handle_request(request)
 
   let assert wisp.WebSocket(upgrade) = response.body
-  let handler = wisp.upgrade_to_websocket(upgrade)
+  let handler = wisp.recover(upgrade)
   let assert Ok(ws) = simulate.create_websocket(handler)
 
   // Send text message
@@ -96,7 +96,7 @@ pub fn websocket_close_test() {
   let response = router.handle_request(request)
 
   let assert wisp.WebSocket(upgrade) = response.body
-  let handler = wisp.upgrade_to_websocket(upgrade)
+  let handler = wisp.recover(upgrade)
   let assert Ok(ws) = simulate.create_websocket(handler)
 
   // Send some messages
@@ -116,7 +116,7 @@ pub fn websocket_closed_ignores_messages_test() {
   let response = router.handle_request(request)
 
   let assert wisp.WebSocket(upgrade) = response.body
-  let handler = wisp.upgrade_to_websocket(upgrade)
+  let handler = wisp.recover(upgrade)
   let assert Ok(ws) = simulate.create_websocket(handler)
 
   // Send a message

src/wisp.gleam

@@ -9,6 +9,7 @@ import gleam/dynamic.{type Dynamic}
 import gleam/dynamic/decode
 import gleam/erlang/application
 import gleam/erlang/atom.{type Atom}
+import gleam/erlang/process
 import gleam/http.{type Method}
 import gleam/http/cookie
 import gleam/http/request.{type Request as HttpRequest}
@@ -75,12 +76,19 @@ pub type Body {
   WebSocket(WebSocketUpgrade)
 }
 
-/// A completely type-safe WebSocket upgrade that maintains type safety
-/// throughout the connection lifecycle without any dynamic casts.
-///
-pub opaque type WebSocketUpgrade {
-  WebSocketUpgrade(ws: websocket.WebSocket)
-}
+pub type WebSocketUpgrade
+
+@internal
+pub type Unknown
+
+@external(erlang, "gleam@function", "identity")
+fn erase(callbacks: websocket.WebSocket(state, message)) -> WebSocketUpgrade
+
+@external(erlang, "gleam@function", "identity")
+@internal
+pub fn recover(
+  upgrade: WebSocketUpgrade,
+) -> websocket.WebSocket(Unknown, Unknown)
 
 /// An alias for a HTTP response containing a `Body`.
 pub type Response =
@@ -2046,16 +2054,20 @@ pub fn get_cookie(
 ///
 pub fn websocket(
   request _request: Request,
-  on_init on_init: fn(websocket.Connection) -> state,
-  on_message on_message: fn(state, websocket.Message, websocket.Connection) ->
+  on_init on_init: fn(websocket.Connection) ->
+    #(state, Option(process.Selector(message))),
+  on_message on_message: fn(
+    state,
+    websocket.Message(custom),
+    websocket.Connection,
+  ) ->
     websocket.Next(state),
   on_close on_close: fn(state) -> Nil,
 ) -> Response {
   let ws = websocket.new(on_init, on_message, on_close)
-  let upgrade = WebSocketUpgrade(ws: ws)
 
   response(200)
-  |> set_body(WebSocket(upgrade))
+  |> set_body(WebSocket(erase(ws)))
 }
 
 //
@@ -2162,8 +2174,3 @@ pub fn csrf_known_header_protection(
     }
   }
 }
-
-@internal
-pub fn upgrade_to_websocket(upgrade: WebSocketUpgrade) -> websocket.WebSocket {
-  upgrade.ws
-}