effect-io-ai

Package: effect
Module: ConfigProvider

ConfigProvider.orElse

Returns a provider that falls back to that when self returns undefined for a path.

When to use

Use to layer multiple config sources, such as env vars plus a defaults file, or provide partial overrides on top of a base config.

Details

Each provider keeps its own path transformations. If the combined provider is later transformed with mapInput or nested, the transformation is applied to both sides.

Gotchas

The fallback only runs when the path is not found (undefined). A SourceError from self is not caught; it propagates immediately.

Example (Falling back to a default provider)

import { ConfigProvider } from "effect"

const envProvider = ConfigProvider.fromEnv({
  env: { HOST: "prod.example.com" }
})
const defaults = ConfigProvider.fromUnknown({ HOST: "localhost", PORT: "3000" })

const combined = ConfigProvider.orElse(envProvider, defaults)

See

• layerAdd – install a fallback provider via a Layer

Signature

declare const orElse: { (that: ConfigProvider): (self: ConfigProvider) => ConfigProvider; (self: ConfigProvider, that: ConfigProvider): ConfigProvider; }

Source

Since v2.0.0