effect-io-ai

Package: effect
Module: Effect

Effect.serviceOption

Optionally accesses a service from the environment.

When to use

Use to read an optional dependency from the current context without making that dependency part of the effect’s required environment.

Details

This function attempts to access a service from the environment. If the service is available, it returns Some(service). If the service is not available, it returns None. Unlike service, this function does not require the service to be present in the environment.

Example (Accessing an optional service)

import { Context, Effect, Option } from "effect"

// Define a service key
const Logger = Context.Service<{
  log: (msg: string) => void
}>("Logger")

// Use serviceOption to optionally access the logger
const program = Effect.gen(function*() {
  const maybeLogger = yield* Effect.serviceOption(Logger)

  if (Option.isSome(maybeLogger)) {
    maybeLogger.value.log("Service is available")
  } else {
    console.log("Service not available")
  }
})

Signature

declare const serviceOption: <I, S>(key: Context.Key<I, S>) => Effect<Option<S>>

Source

Since v2.0.0