import Observable, { UnaryFn } from "./Observable";
/** Simple transform function */
export declare function map<T, R>(...fns: Array<UnaryFn<T, R>>): (source: Observable<T>) => Observable<R>;
/** Only pass value if it is different from the last one */
export declare function changed<T>(fn?: (last: T, current: T) => boolean): (source: Observable<T>) => Observable<T>;
/** Only pass value if it has never been seen before */
export declare function distinct<T>(): (source: Observable<T>) => Observable<T>;
/** Delay each event by n ms */
export declare function delay<T>(ms: number): (source: Observable<T>) => Observable<T>;
/** Only take the latest event and delay by n ms */
export declare function debounce<T>(ms: number): (source: Observable<T>) => Observable<T>;
/** Drop values unntil the timer is up */
export declare function throttle<T>(ms: number): (source: Observable<T>) => Observable<T>;
/** Reduce over emitted values */
export declare function scan<T>(fn?: (acc: T, x: T) => T): (source: Observable<T>) => Observable<T>;
/** Collect n emitted values and complete */
export declare function take<T>(n: number): (source: Observable<T>) => Observable<T>;
/** Collect n emitted values and complete */
export declare function filter<T>(fn: (x: T) => boolean): (source: Observable<T>) => Observable<T>;
/** Map over outer + inner observable and emit all values */
export declare function flatMap<T, R>(fn: (x: T) => Observable<R>): (source: Observable<T>) => Observable<R>;
/** Only emit from inner observable as long as we are subscribed */
export declare function switchMap<T, R>(fn: (x: T) => Observable<R>): (source: Observable<T>) => Observable<R>;