mist

Wist adapter for the Mist web server.

This module implements the transport adapter bridging Mist’s WebSocket upgrade logic and connection actor loops to Wist’s transport-neutral Handler API.

Use upgrade inside your Mist HTTP request handler to switch protocols and run a stateful Wist handler.

Values

upgrade

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pub fn upgrade(
  request: request.Request(mist.Connection),
  handler: wist.Handler(state, inbound, outbound),
  codec: wist.Codec(inbound, outbound),
) -> response.Response(mist.ResponseData)

Upgrades an incoming HTTP request to a WebSocket connection managed by Wist.

If the request is a valid WebSocket handshake request, it returns a 101 Switching Protocols response body configured to spawn Mist’s WebSocket handler process. If the request is malformed or invalid, a 400 Bad Request response is returned.

Parameters

request: The incoming HTTP request carrying the Mist transport Connection.
handler: The stateful wist.Handler defining initial state and event transitions.
codec: A wist.Codec specifying how to encode and decode wire frames.

Guarantees

Serialization: Connection events are processed strictly sequentially. update is never run concurrently.
FIFO Effects: Effects returned by update are executed in the exact order they are listed.
Safety: If frame decoding fails, the connection is closed immediately, and a Failed event is dispatched.

Limitations

Outbound pings are supported via the wist.Ping effect, but client Pong frames are swallowed by Mist’s internal wrapper and will not be dispatched as events.

Example

import wist
import wist/adapters/mist as wist_mist

fn my_http_handler(req) {
  case req.path {
    "/ws" -> wist_mist.upgrade(req, my_ws_handler, wist.raw_codec())
    _ -> response.new(200)
  }
}