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beryl: real-time channels for Gleam

Type-safe real-time channels and presence for Gleam, targeting the Erlang (BEAM) runtime.

Quick StartWhat is beryl?
room_channel.gleam
import beryl/channel
import gleam/json


// One handler per topic pattern, with private typed state.
pub fn room() -> channel.Handler {
  channel.handler("room:*", fn(ctx) {
    channel.accept(0)
    |> channel.on_message(fn(count, msg: channel.Message) {
      case msg.event {
        "new_msg" ->
          channel.next(count + 1, [
            channel.broadcast("new_msg", json.int(count + 1)),
          ])
        _ -> channel.stay(count)
      }
    })
    |> channel.with_reply(json.string(ctx.topic))
  })
}

Build your first beryl app

Section titled “Build your first beryl app”

  1. Install beryl

    Install beryl packages from GitHub. Add beryl and one WebSocket transport as Git dependencies. The beryl package includes the channel layer.

    gleam deps download

    Installation guide →

  2. Build your first socket app

    Write a channel handler. Connect the WebSocket transport and a Phoenix JS client. If you want to control routing, compare the two APIs.

    Open the Quick Start →

  3. Run an example

    Use a complete example. Then read the channel guide or the API reference.

    View examples →

What beryl provides

Section titled “What beryl provides”

Choose handlers or one update function

Register one handler for each topic pattern. beryl/channel routes each event to the correct channel. Each channel keeps private, typed state. You can also route all events in one typed update function.

Choose an API →

Track who is connected

Track connected users across Erlang nodes. A conflict-free replicated data type (CRDT) resolves joins and leaves that happen at the same time.

Presence guide →

Broadcast across Erlang nodes

Send events between connected Erlang nodes through pg process groups. You do not need a separate message broker.

PubSub guide →