import type {
	Head,
	IsomorphicIterable,
	IsomorphicIterableItem,
	Maybe,
	ReadOnlyArray,
} from "@lou.codes/types";
/**
 * Get first element of an iterable or asynchronous iterable (`undefined` if
 * it is empty).
 *
 * @category Asynchronous Reducers
 * @example
 * ```typescript
 * head([1, 2, 3]); // 1
 * ```
 * @param iterable Iterable to get the first element from.
 * @returns First element of the iterable (`undefined` if empty).
 */
export declare const head: <Iterable extends IsomorphicIterable>(
	iterable: Iterable,
) => Iterable extends ReadOnlyArray ? Head<Iterable>
:	Maybe<IsomorphicIterableItem<Iterable>>;