import { IndexedSelector } from "../types/IndexedSelector";
/**
 * Maps each element to an iterable and yields every item from the flattened results in source order.
 *
 * @typeParam T - Element type produced by the source iterable.
 * @typeParam TOut - Element type emitted by the projected iterables.
 * @param src - Source iterable enumerated to supply values to `selector`.
 * @param selector - Projection invoked with the current value and index to produce an iterable of results.
 * @returns A deferred iterable yielding items from each projected iterable sequentially.
 *
 * @example
 * ```ts
 * const values = [..._flatMap([1, 2], (n) => [n, n * 10])];
 * console.log(values); // [1, 10, 2, 20]
 * ```
 *
 * or using the curried version:
 * ```ts
 * const values = pipeInto(
 *   ["a", "b"],
 *   flatMap((value, index) => [`${value}${index}`, `${value.toUpperCase()}${index}`])
 * );
 * console.log([...values]); // ["a0", "A0", "b1", "B1"]
 * ```
 */
export declare function _flatMap<T, TOut>(src: Iterable<T>, selector: IndexedSelector<T, Iterable<TOut>>): Iterable<TOut>;
/**
 * Curried version of {@link _flatMap}.
 */
export declare const flatMap: <T, TOut>(selector: IndexedSelector<T, Iterable<TOut>>) => (src: Iterable<T>) => Iterable<TOut>;