fix: remove the ability for users to contruct websocket types

src/wisp.gleam

@@ -1915,17 +1915,20 @@ pub type WsMessage(a) {
 /// This connection is used from within a websocket handler function to
 /// send data to the client via `WsSendText` or `WsSendBinary`
 ///
-pub type WsConnection =
+type WsConnection =
   fn(WsSend) -> Result(Nil, WsError)
 
-/// A socket connection used to connect to clients.
+/// A capability used to support websocket execution from a capable server.
 ///
 /// This is provided by a websocket capable server's handler
 /// function. It is required to turn a http connection into an
 /// active websocket (`WsConnection`).
 ///
 pub type WsCapability(state, msg) {
-  WsCapability(fn(Request, WsHandler(state, msg)) -> Response)
+  WsCapability(
+    handler: fn(Request, WsHandler(state, msg)) -> Response,
+    ws: internal.WsCapability,
+  )
 }
 
 /// Configuration for a websockets creation and life-cycle.
@@ -2049,8 +2052,8 @@ pub type WsError {
 /// Start a websocket session.
 ///
 /// This takes all the parameters required to begin a websocket session with a
-/// client and requires a websocket capabile web server such as mist which
-/// provides the `WsCapability` as part of it's handler function.
+/// client and requires a websocket capable web server such as mist which
+/// provides the `WsCapability` as part of its handler function.
 ///
 /// ```gleam
 /// wisp.WsHandler(handler, on_init, on_close) |> wisp.websocket(req, ws_capability)
@@ -2061,6 +2064,6 @@ pub fn websocket(
   req: Request,
   capability: WsCapability(state, msg),
 ) -> Response {
-  let WsCapability(do_websocket) = capability
+  let WsCapability(do_websocket, _) = capability
   do_websocket(req, handler)
 }

src/wisp/internal.gleam

@@ -82,3 +82,14 @@ pub fn random_string(length: Int) -> String {
 pub fn random_slug() -> String {
   random_string(16)
 }
+
+//
+// Websockets
+//
+
+/// A type used purely to block the user constructing a `wisp.WsCapability`
+/// via the public api as it should only be constructed by the web server if it
+/// supports websockets.
+pub type WsCapability {
+  WsCapability
+}

src/wisp/wisp_mist.gleam

@@ -59,7 +59,7 @@ pub fn handler(
       fn(req: wisp.Request, wsh: wisp.WsHandler(a, b)) -> wisp.Response {
         request.set_body(req, mist) |> websocket(wsh)
       }
-      |> wisp.WsCapability
+      |> wisp.WsCapability(internal.WsCapability)
 
     let response =
       request