import { Immutable, ImmutableArray, Prop, UnionTupleType } from "@fretve/global-types";
import { Observable } from "rxjs";
declare type StateSlice<TState, TProps extends Prop<TState>[]> = {
    [P in UnionTupleType<TProps>]: TState[P];
};
/** An rxjs operator used to select a specified slice from state
 *  and only emit when its value changes.
 * @param props - The properties on state that should be selected.
 * @returns The slice of state that corresponds with the specified properties
 */
export declare const selectState: <TState, TProps extends Extract<keyof TState, string>[] = Extract<keyof TState, string>[]>(props: ImmutableArray<Extract<keyof TState, string>>) => (source: Observable<Immutable<TState>>) => Observable<Immutable<StateSlice<TState, TProps>>>;
export {};