import { IObservable } from '../internal/Observable';
export declare type TPredicate<T> = {
    (value: T): boolean;
};
export declare type TSource<T> = IObservable<T>;
export declare type TResult<T> = IObservable<T>;
export declare const filter: {
    <T>(predicate: TPredicate<T>, source: IObservable<T>): IObservable<T>;
    <T>(predicate: TPredicate<T>): (source: IObservable<T>) => IObservable<T>;
};