Prelude vs Layer

The prelude and layer fields in ActorRuntime.make(...) serve different lifetimes.

Use prelude for long-lived infrastructure:

• database access
• config
• logging
• asset bindings
• Cloudflare service bindings

Use layer for short-lived context derived from the current client-specific actor invocation:

• current user id
• current authorization

Derive request context

The next example builds a layer that provides an actor-specific CurrentUserId derived from two different actor definitions.

 
export class CurrentUserId extends Context.Service<
  CurrentUserId,
  typeof UserId.Type
>()("CurrentUserId") {}
 
// Use the actor name as the id.
export const layerLobby = Effect.gen(function* () {
  const { name } = yield* LobbyActor
  return name
}).pipe(Layer.effect(CurrentUserId))
 
// Use the current client attachment as the id.
export const layerChat = Effect.gen(function* () {
  const { currentClient } = yield* ChatActor
  const { userId } = yield* currentClient.attachments
  return userId
}).pipe(Layer.effect(CurrentUserId))

In Effect v4, context is defined with Context.Service<Self, A>()(id). This replaces Context.Tag from earlier versions.

Read Actor Context for the values available through yield* ActorTag.