import { EqualityComparator, ReadonlyStore } from './store.js';
/**
 * Configurations for derived stores.
 */
export type DerivedStoreConfig<T> = {
    /**
     * (optional, defaults to `(a, b) => a === b`) a function that's used to determine if the current value of the store value is different from
     * the one being set and thus if the store needs to be updated and the subscribers notified.
     */
    comparator?: EqualityComparator<T>;
};
/**
 * Create a derived store.
 *
 * Example usage:
 * ```ts
 * const source$ = makeStore(10);
 * const derived$ = makeDerivedStore(source$, (v) => v * 2);
 * source$.subscribe((v) => console.log(v)); // prints 10
 * derived$.subscribe((v) => console.log(v)); // prints 20
 * source$.set(16); // triggers both console.logs, printing 16 and 32
 * ```
 * @param readonlyStore a store or readonly store.
 * @param map a function that takes the current value of the source store and maps it to another value.
 * @param config a {@link DerivedStoreConfig} which contains configuration information such as a value comparator to avoid needless notifications to subscribers.
 */
export declare function makeDerivedStore<TIn, TOut>(readonlyStore: ReadonlyStore<TIn>, map: (value: TIn) => TOut, config?: DerivedStoreConfig<TOut>): ReadonlyStore<TOut>;
/**
 * Create a derived store from multiple sources.
 *
 * Example usage:
 * ```ts
 * const source1$ = makeStore(10);
 * const source2$ = makeStore(-10);
 * const derived$ = makeDerivedStore([source1$, source2$], ([v1, v2]) => v1 + v2);
 * source1$.subscribe((v) => console.log(v)); // prints 10
 * source2$.subscribe((v) => console.log(v)); // prints -10
 * derived$.subscribe((v) => console.log(v)); // prints 0
 * source1$.set(11); // prints 11 (first console.log) and 1 (third console.log)
 * source2$.set(9); // prints 9 (second console.log) and 20 (third console.log)
 * ```
 * @param readonlyStores an array of stores or readonly stores.
 * @param map a function that takes the current value of all the source stores and maps it to another value.
 * @param config a {@link DerivedStoreConfig} which contains configuration information such as a value comparator to avoid needless notifications to subscribers.
 */
export declare function makeDerivedStore<TIn extends unknown[] | [unknown, ...unknown[]], TOut>(readonlyStores: {
    [K in keyof TIn]: ReadonlyStore<TIn[K]>;
}, map: (value: {
    [K in keyof TIn]: TIn[K];
}) => TOut, config?: DerivedStoreConfig<TOut>): ReadonlyStore<TOut>;
/**
 * Create a derived store from multiple sources.
 *
 * Example usage:
 * ```ts
 * const source1$ = makeStore(10);
 * const source2$ = makeStore(-10);
 * const derived$ = makeDerivedStore({v1: source1$, v2: source2$}, ({v1, v2}) => v1 + v2);
 * source1$.subscribe((v) => console.log(v)); // prints 10
 * source2$.subscribe((v) => console.log(v)); // prints -10
 * derived$.subscribe((v) => console.log(v)); // prints 0
 * source1$.set(11); // prints 11 (first console.log) and 1 (third console.log)
 * source2$.set(9); // prints 9 (second console.log) and 20 (third console.log)
 * ```
 * @param readonlyStores an array of stores or readonly stores.
 * @param map a function that takes the current value of all the source stores and maps it to another value.
 * @param config a {@link DerivedStoreConfig} which contains configuration information such as a value comparator to avoid needless notifications to subscribers.
 */
export declare function makeDerivedStore<TIn, TOut>(readonlyStores: {
    [K in keyof TIn]: ReadonlyStore<TIn[K]>;
}, map: (value: {
    [K in keyof TIn]: TIn[K];
}) => TOut, config?: DerivedStoreConfig<TOut>): ReadonlyStore<TOut>;