Method refine

repos/effect/packages/effect/src/Optic.ts:687–687

* Narrows the focus to a subtype `B` using a type guard. * * **Details** * * - On a Prism, returns a Prism. * - On an Optional, returns an Optional. * - Pass optional `annotations` to customize the error message. * * **Example** (Narrowing a union) * * `

(
    this: Prism<S, A>,
    refinement: (a: A) => a is B,
    annotations?: Schema.Annotations.Filter
  )

   *   inner issue is {@link SchemaIssue.MissingKey}, for both `getResult` and
   *   `replaceResult`.
   *
   * **Example** (Accessing records safely)
   *
   * ```ts import.meta.vitest