Function factory

repos/effect/packages/effect/src/unstable/reactivity/Atom.ts:728–753

(
    create:
      | Layer.Layer<R, E, AtomRegistry | Reactivity.Reactivity>
      | ((get: AtomContext) => Layer.Layer<R, E, AtomRegistry | Reactivity.Reactivity>)
  )

  readonly memoMap: Atom<Layer.MemoMap>
}

/**
 * A `RuntimeFactory` backed by a concrete memo map shared across registries.
 *
 * @category models
 * @since 4.0.0
 */
export interface SharedRuntimeFactory extends RuntimeFactory {
  readonly memoMap: Layer.MemoMap
}

/**
 * Creates a `RuntimeFactory` backed by a registry-scoped memo map by default,
 * or by the supplied atom or concrete `Layer.MemoMap`.
 *
 * @category constructors
 * @since 4.0.0
 */
export function context(): RegistryRuntimeFactory
export function context(options: { readonly memoMap: Atom<Layer.MemoMap> }): RegistryRuntimeFactory
export function context(options: { readonly memoMap: Layer.MemoMap }): SharedRuntimeFactory
export function context(options?: {
  readonly memoMap: Atom<Layer.MemoMap> | Layer.MemoMap
}): RegistryRuntimeFactory | SharedRuntimeFactory {
  const memoMap = options?.memoMap ?? removeTtl(make(() => Layer.makeMemoMapUnsafe()))
  const resolveMemoMap = (get: AtomContext): Layer.MemoMap => isAtom(memoMap) ? get(memoMap) : memoMap
  let globalLayer: Layer.Layer<any, any, AtomRegistry> = Reactivity.layer
  function factory<E, R>(
    create: