import { IndexedSelector } from "../types/IndexedSelector";
import { SetFactory } from "../types/SetFactory";
/**
 * Materializes a sequence into a set, optionally projecting each element to a key before insertion.
 *
 * @typeParam T - Element type produced by the source iterable.
 * @typeParam TKey - Key type returned by `keySelector` when supplied.
 * @param src - Source iterable to materialize.
 * @param keySelector - Optional projection used to derive the value stored in the set; defaults to the element itself.
 * @param setFactory - Optional factory controlling the concrete set implementation to instantiate.
 * @returns A set containing one entry per projected value.
 * @throws {Error} If `keySelector` produces the same key more than once.
 * @example
 * ```ts
 * const lengths = _toSet(["a", "bb", "ccc"], (value) => value.length);
 * console.log([...lengths]); // [1, 2, 3]
 * ```
 */
export declare function _toSet<T>(src: Iterable<T>, setFactory?: SetFactory<T>): Set<T>;
export declare function _toSet<T, TKey>(src: Iterable<T>, keySelector: IndexedSelector<T, TKey>, setFactory?: SetFactory<TKey>): Set<TKey>;
/**
 * Curried version of {@link _toSet}.
 */
export declare function toSet<T>(setFactory?: SetFactory<T>): (src: Iterable<T>) => Set<T>;
export declare function toSet<T, TKey>(keySelector: IndexedSelector<T, TKey>, setFactory?: SetFactory<TKey>): (src: Iterable<T>) => Set<TKey>;