import type { PartialObserver } from './Observer.js';
import type { Unsubscribable } from './Unsubscribable.js';
/**
 * Lazy and composable push-based data source.
 *
 * @since 1.0.0
 */
export interface Subscribable<out D = unknown> {
    __type?: D;
    /**
     * Subscribe to a subscribable using an observer.
     * @param observer
     *
     * @since 1.0.0
     */
    subscribe(observer: PartialObserver<D>): Unsubscribable;
}
/**
 * Object holding a {@link Subscribable} feature
 *
 * @since 1.0.0
 */
export interface SubscribableHolder<out D = unknown> {
    [Symbol.observable](): Subscribable<D>;
}
export type AnySubscribable<D = unknown> = Subscribable<D> | SubscribableHolder<D>;
export type SubscribableValue<T extends AnySubscribable> = T extends AnySubscribable<infer D> ? D : never;