diff --git a/rx/rx-lite.d.ts b/rx/rx-lite.d.ts
index 3a4ee18450..5bae390cc9 100644
--- a/rx/rx-lite.d.ts
+++ b/rx/rx-lite.d.ts
@@ -225,48 +225,48 @@ declare namespace Rx {
 		catchException(handler: (exception: any) => IPromise<T>): Observable<T>;	// alias for catch
 		catch(second: Observable<T>): Observable<T>;
 		catchException(second: Observable<T>): Observable<T>;	// alias for catch
-		combineLatest<T2, TResult>(second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		combineLatest<T2, TResult>(second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
-		combineLatest<TOther, TResult>(souces: Observable<TOther>[], resultSelector: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
-		combineLatest<TOther, TResult>(souces: IPromise<TOther>[], resultSelector: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
-		withLatestFrom<T2, TResult>(second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T2, TResult>(second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
-		withLatestFrom<TOther, TResult>(souces: Observable<TOther>[], resultSelector: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
-		withLatestFrom<TOther, TResult>(souces: IPromise<TOther>[], resultSelector: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
+		combineLatest<T2, TResult>(second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T2, TResult>(second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
+		combineLatest<TOther, TResult>(souces: Observable<TOther>[], resultSelector?: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
+		combineLatest<TOther, TResult>(souces: IPromise<TOther>[], resultSelector?: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
+		withLatestFrom<T2, TResult>(second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T2, TResult>(second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
+		withLatestFrom<TOther, TResult>(souces: Observable<TOther>[], resultSelector?: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
+		withLatestFrom<TOther, TResult>(souces: IPromise<TOther>[], resultSelector?: (firstValue: T, ...otherValues: TOther[]) => TResult): Observable<TResult>;
 		concat(...sources: Observable<T>[]): Observable<T>;
 		concat(...sources: IPromise<T>[]): Observable<T>;
 		concat(sources: Observable<T>[]): Observable<T>;
 		concat(sources: IPromise<T>[]): Observable<T>;
 		concatAll(): T;
 		concatObservable(): T;	// alias for concatAll
-		concatMap<T2, R>(selector: (value: T, index: number) => Observable<T2>, resultSelector: (value1: T, value2: T2, index: number) => R): Observable<R>;	// alias for selectConcat
-		concatMap<T2, R>(selector: (value: T, index: number) => IPromise<T2>, resultSelector: (value1: T, value2: T2, index: number) => R): Observable<R>;	// alias for selectConcat
+		concatMap<T2, R>(selector: (value: T, index: number) => Observable<T2>, resultSelector?: (value1: T, value2: T2, index: number) => R): Observable<R>;	// alias for selectConcat
+		concatMap<T2, R>(selector: (value: T, index: number) => IPromise<T2>, resultSelector?: (value1: T, value2: T2, index: number) => R): Observable<R>;	// alias for selectConcat
 		concatMap<R>(selector: (value: T, index: number) => Observable<R>): Observable<R>;	// alias for selectConcat
 		concatMap<R>(selector: (value: T, index: number) => IPromise<R>): Observable<R>;	// alias for selectConcat
 		concatMap<R>(selector: (value: T, index: number) => R[]): Observable<R>;	// alias for selectConcat
@@ -283,23 +283,23 @@ declare namespace Rx {
 		switchLatest(): T;	// alias for switch
 		takeUntil<T2>(other: Observable<T2>): Observable<T>;
 		takeUntil<T2>(other: IPromise<T2>): Observable<T>;
-		zip<T2, TResult>(second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		zip<T2, TResult>(second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		zip<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		zip<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		zip<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		zip<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		zip<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
-		zip<TOther, TResult>(second: Observable<TOther>[], resultSelector: (left: T, ...right: TOther[]) => TResult): Observable<TResult>;
-		zip<TOther, TResult>(second: IPromise<TOther>[], resultSelector: (left: T, ...right: TOther[]) => TResult): Observable<TResult>;
+		zip<T2, TResult>(second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		zip<T2, TResult>(second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		zip<T2, T3, TResult>(second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		zip<T2, T3, TResult>(second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		zip<T2, T3, TResult>(second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		zip<T2, T3, TResult>(second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, TResult>(second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		zip<T2, T3, T4, T5, TResult>(second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
+		zip<TOther, TResult>(second: Observable<TOther>[], resultSelector?: (left: T, ...right: TOther[]) => TResult): Observable<TResult>;
+		zip<TOther, TResult>(second: IPromise<TOther>[], resultSelector?: (left: T, ...right: TOther[]) => TResult): Observable<TResult>;
 
 		asObservable(): Observable<T>;
 		dematerialize<TOrigin>(): Observable<TOrigin>;
@@ -348,15 +348,15 @@ declare namespace Rx {
 		select<TResult>(selector: (value: T, index: number, source: Observable<T>) => TResult, thisArg?: any): Observable<TResult>;
 		map<TResult>(selector: (value: T, index: number, source: Observable<T>) => TResult, thisArg?: any): Observable<TResult>;	// alias for select
 		pluck<TResult>(prop: string): Observable<TResult>;
-		selectMany<TOther, TResult>(selector: (value: T) => Observable<TOther>, resultSelector: (item: T, other: TOther) => TResult): Observable<TResult>;
-		selectMany<TOther, TResult>(selector: (value: T) => IPromise<TOther>, resultSelector: (item: T, other: TOther) => TResult): Observable<TResult>;
+		selectMany<TOther, TResult>(selector: (value: T) => Observable<TOther>, resultSelector?: (item: T, other: TOther) => TResult): Observable<TResult>;
+		selectMany<TOther, TResult>(selector: (value: T) => IPromise<TOther>, resultSelector?: (item: T, other: TOther) => TResult): Observable<TResult>;
 		selectMany<TResult>(selector: (value: T) => Observable<TResult>): Observable<TResult>;
 		selectMany<TResult>(selector: (value: T) => IPromise<TResult>): Observable<TResult>;
 		selectMany<TResult>(other: Observable<TResult>): Observable<TResult>;
 		selectMany<TResult>(other: IPromise<TResult>): Observable<TResult>;
 		selectMany<TResult>(selector: (value: T) => TResult[]): Observable<TResult>;	// alias for selectMany
-		flatMap<TOther, TResult>(selector: (value: T) => Observable<TOther>, resultSelector: (item: T, other: TOther) => TResult): Observable<TResult>;	// alias for selectMany
-		flatMap<TOther, TResult>(selector: (value: T) => IPromise<TOther>, resultSelector: (item: T, other: TOther) => TResult): Observable<TResult>;	// alias for selectMany
+		flatMap<TOther, TResult>(selector: (value: T) => Observable<TOther>, resultSelector?: (item: T, other: TOther) => TResult): Observable<TResult>;	// alias for selectMany
+		flatMap<TOther, TResult>(selector: (value: T) => IPromise<TOther>, resultSelector?: (item: T, other: TOther) => TResult): Observable<TResult>;	// alias for selectMany
 		flatMap<TResult>(selector: (value: T) => Observable<TResult>): Observable<TResult>;	// alias for selectMany
 		flatMap<TResult>(selector: (value: T) => IPromise<TResult>): Observable<TResult>;	// alias for selectMany
 		flatMap<TResult>(other: Observable<TResult>): Observable<TResult>;	// alias for selectMany
@@ -383,8 +383,8 @@ declare namespace Rx {
 		 */
 		flatMapObserver<T2, T3, T4>(onNext: (value: T, index: number) => Observable<T2>, onError: (exception: any) => Observable<T3>, onCompleted: () => Observable<T4>, thisArg?: any): Observable<T2 | T3 | T4>;
 
-		selectConcat<T2, R>(selector: (value: T, index: number) => Observable<T2>, resultSelector: (value1: T, value2: T2, index: number) => R): Observable<R>;
-		selectConcat<T2, R>(selector: (value: T, index: number) => IPromise<T2>, resultSelector: (value1: T, value2: T2, index: number) => R): Observable<R>;
+		selectConcat<T2, R>(selector: (value: T, index: number) => Observable<T2>, resultSelector?: (value1: T, value2: T2, index: number) => R): Observable<R>;
+		selectConcat<T2, R>(selector: (value: T, index: number) => IPromise<T2>, resultSelector?: (value1: T, value2: T2, index: number) => R): Observable<R>;
 		selectConcat<R>(selector: (value: T, index: number) => Observable<R>): Observable<R>;
 		selectConcat<R>(selector: (value: T, index: number) => IPromise<R>): Observable<R>;
 		selectConcat<R>(sequence: Observable<R>): Observable<R>;
@@ -524,7 +524,7 @@ declare namespace Rx {
 		fromArray<T>(array: T[], scheduler?: IScheduler): Observable<T>;
 		fromArray<T>(array: { length: number;[index: number]: T; }, scheduler?: IScheduler): Observable<T>;
 
-		generate<TState, TResult>(initialState: TState, condition: (state: TState) => boolean, iterate: (state: TState) => TState, resultSelector: (state: TState) => TResult, scheduler?: IScheduler): Observable<TResult>;
+		generate<TState, TResult>(initialState: TState, condition: (state: TState) => boolean, iterate: (state: TState) => TState, resultSelector?: (state: TState) => TResult, scheduler?: IScheduler): Observable<TResult>;
 		never<T>(): Observable<T>;
 
 		/**
@@ -575,73 +575,73 @@ declare namespace Rx {
 		catchError<T>(...sources: IPromise<T>[]): Observable<T>;	// alias for catch
 
 		combineLatest<T, T2>(first: Observable<T>, second: Observable<T2>): Observable<[T, T2]>;
-		combineLatest<T, T2, TResult>(first: Observable<T>, second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		combineLatest<T, T2, TResult>(first: IPromise<T>, second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		combineLatest<T, T2, TResult>(first: Observable<T>, second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		combineLatest<T, T2, TResult>(first: IPromise<T>, second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T, T2, TResult>(first: Observable<T>, second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T, T2, TResult>(first: IPromise<T>, second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T, T2, TResult>(first: Observable<T>, second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		combineLatest<T, T2, TResult>(first: IPromise<T>, second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
 		combineLatest<T, T2, T3>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>): Observable<[T, T2, T3]>;
-		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
 		combineLatest<T, T2, T3, T4>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>): Observable<[T, T2, T3, T4]>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
 		combineLatest<T, T2, T3, T4, T5>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>): Observable<[T, T2, T3, T4, T5]>;
-		combineLatest<T, T2, T3, T4, T5, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
+		combineLatest<T, T2, T3, T4, T5, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
 		combineLatest<T>(sources: Observable<T>[]): Observable<T[]>;
-		combineLatest<TOther, TResult>(sources: Observable<TOther>[], resultSelector: (...otherValues: TOther[]) => TResult): Observable<TResult>;
-		combineLatest<TOther, TResult>(sources: IPromise<TOther>[], resultSelector: (...otherValues: TOther[]) => TResult): Observable<TResult>;
+		combineLatest<TOther, TResult>(sources: Observable<TOther>[], resultSelector?: (...otherValues: TOther[]) => TResult): Observable<TResult>;
+		combineLatest<TOther, TResult>(sources: IPromise<TOther>[], resultSelector?: (...otherValues: TOther[]) => TResult): Observable<TResult>;
 
-		withLatestFrom<T, T2, TResult>(first: Observable<T>, second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, TResult>(first: IPromise<T>, second: Observable<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, TResult>(first: Observable<T>, second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, TResult>(first: IPromise<T>, second: IPromise<T2>, resultSelector: (v1: T, v2: T2) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
-		withLatestFrom<T, T2, T3, T4, T5, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
-		withLatestFrom<TOther, TResult>(souces: Observable<TOther>[], resultSelector: (...otherValues: TOther[]) => TResult): Observable<TResult>;
-		withLatestFrom<TOther, TResult>(souces: IPromise<TOther>[], resultSelector: (...otherValues: TOther[]) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, TResult>(first: Observable<T>, second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, TResult>(first: IPromise<T>, second: Observable<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, TResult>(first: Observable<T>, second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, TResult>(first: IPromise<T>, second: IPromise<T2>, resultSelector?: (v1: T, v2: T2) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, resultSelector?: (v1: T, v2: T2, v3: T3) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: Observable<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: Observable<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: Observable<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: Observable<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, TResult>(first: IPromise<T>, second: IPromise<T2>, third: IPromise<T3>, fourth: IPromise<T4>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4) => TResult): Observable<TResult>;
+		withLatestFrom<T, T2, T3, T4, T5, TResult>(first: Observable<T>, second: Observable<T2>, third: Observable<T3>, fourth: Observable<T4>, fifth: Observable<T5>, resultSelector?: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => TResult): Observable<TResult>;
+		withLatestFrom<TOther, TResult>(souces: Observable<TOther>[], resultSelector?: (...otherValues: TOther[]) => TResult): Observable<TResult>;
+		withLatestFrom<TOther, TResult>(souces: IPromise<TOther>[], resultSelector?: (...otherValues: TOther[]) => TResult): Observable<TResult>;
 
 		concat<T>(...sources: Observable<T>[]): Observable<T>;
 		concat<T>(...sources: IPromise<T>[]): Observable<T>;
@@ -658,23 +658,23 @@ declare namespace Rx {
 
 		pairs<T>(obj: { [key: string]: T }, scheduler?: IScheduler): Observable<[string, T]>;
 
-		zip<T1, T2, TResult>(first: Observable<T1>, sources: Observable<T2>[], resultSelector: (item1: T1, ...right: T2[]) => TResult): Observable<TResult>;
-		zip<T1, T2, TResult>(first: Observable<T1>, sources: IPromise<T2>[], resultSelector: (item1: T1, ...right: T2[]) => TResult): Observable<TResult>;
-		zip<T1, T2, TResult>(source1: Observable<T1>, source2: Observable<T2>, resultSelector: (item1: T1, item2: T2) => TResult): Observable<TResult>;
-		zip<T1, T2, TResult>(source1: Observable<T1>, source2: IPromise<T2>, resultSelector: (item1: T1, item2: T2) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, resultSelector: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, resultSelector: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, resultSelector: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, resultSelector: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: Observable<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: IPromise<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, source4: Observable<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, source4: IPromise<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, source4: Observable<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, source4: IPromise<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, source4: Observable<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, source4: IPromise<T4>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
-		zip<T1, T2, T3, T4, T5, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: Observable<T4>, source5: Observable<T5>, resultSelector: (item1: T1, item2: T2, item3: T3, item4: T4, item5: T5) => TResult): Observable<TResult>;
+		zip<T1, T2, TResult>(first: Observable<T1>, sources: Observable<T2>[], resultSelector?: (item1: T1, ...right: T2[]) => TResult): Observable<TResult>;
+		zip<T1, T2, TResult>(first: Observable<T1>, sources: IPromise<T2>[], resultSelector?: (item1: T1, ...right: T2[]) => TResult): Observable<TResult>;
+		zip<T1, T2, TResult>(source1: Observable<T1>, source2: Observable<T2>, resultSelector?: (item1: T1, item2: T2) => TResult): Observable<TResult>;
+		zip<T1, T2, TResult>(source1: Observable<T1>, source2: IPromise<T2>, resultSelector?: (item1: T1, item2: T2) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, resultSelector?: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, resultSelector?: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, resultSelector?: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, resultSelector?: (item1: T1, item2: T2, item3: T3) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: Observable<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: IPromise<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, source4: Observable<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: IPromise<T3>, source4: IPromise<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, source4: Observable<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: Observable<T3>, source4: IPromise<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, source4: Observable<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, TResult>(source1: Observable<T1>, source2: IPromise<T2>, source3: IPromise<T3>, source4: IPromise<T4>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4) => TResult): Observable<TResult>;
+		zip<T1, T2, T3, T4, T5, TResult>(source1: Observable<T1>, source2: Observable<T2>, source3: Observable<T3>, source4: Observable<T4>, source5: Observable<T5>, resultSelector?: (item1: T1, item2: T2, item3: T3, item4: T4, item5: T5) => TResult): Observable<TResult>;
 		zipArray<T>(...sources: Observable<T>[]): Observable<T[]>;
 		zipArray<T>(sources: Observable<T>[]): Observable<T[]>;