diff --git a/package-lock.json b/package-lock.json
index f6bdc65..2b69e18 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16058,9 +16058,9 @@
       "dev": true
     },
     "typescript": {
-      "version": "2.9.2",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-2.9.2.tgz",
-      "integrity": "sha512-Gr4p6nFNaoufRIY4NMdpQRNmgxVIGMs4Fcu/ujdYk3nAZqk7supzBE9idmvfZIlH/Cuj//dvi+019qEue9lV0w==",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.0.1.tgz",
+      "integrity": "sha512-zQIMOmC+372pC/CCVLqnQ0zSBiY7HHodU7mpQdjiZddek4GMj31I3dUJ7gAs9o65X7mnRma6OokOkc6f9jjfBg==",
       "dev": true
     },
     "uglify-js": {
diff --git a/package.json b/package.json
index 9bf56a6..9d43512 100644
--- a/package.json
+++ b/package.json
@@ -86,7 +86,7 @@
     "tslint-config-prettier": "^1.10.0",
     "tslint-config-standard": "^7.0.0",
     "tslint-eslint-rules": "^5.3.1",
-    "typescript": "^2.8.1"
+    "typescript": "^3.0.1"
   },
   "config": {
     "commitizen": {
diff --git a/src/core/Observable.ts b/src/core/Observable.ts
index 76f32a3..f044c82 100644
--- a/src/core/Observable.ts
+++ b/src/core/Observable.ts
@@ -1,6 +1,7 @@
 // tslint:disable max-classes-per-file no-use-before-declare
 import $$observable from 'symbol-observable'
 import {
+  ArrayValues,
   Disposer,
   PartialObserver,
   SignalType,
@@ -190,18 +191,13 @@ class ConcreteObserver<T> implements SubscriptionObserver<T> {
 }
 
 export class Observable<T> implements Subscribable<T> {
-  static of(): Observable<any>
-  static of<A>(a: A): Observable<A>
-  static of<A, B>(a: A, b: B): Observable<A | B>
-  static of<A, B, C>(a: A, b: B, c: C): Observable<A | B | C>
-  static of<A, B, C, D>(a: A, b: B, c: C, d: D): Observable<A | B | C | D>
-  static of<A, B, C, D, E>(a: A, b: B, c: C, d: D, e: E): Observable<A | B | C | D | E>
+  static of<TS extends any[]>(...args: TS): Observable<ArrayValues<TS>>
   static of() {
     const C = typeof this === 'function' ? this : Observable
     return new C(fromArray(arguments))
   }
 
-  static from<A>(ish: Observable<A> | Iterable<A>) {
+  static from<A>(ish: Subscribable<A> | Observable<A> | Iterable<A>) {
     const C = typeof this === 'function' ? this : Observable
     const error = `${ish} is not an object`
 
diff --git a/src/core/types.h.ts b/src/core/types.h.ts
index 6919771..72c1677 100644
--- a/src/core/types.h.ts
+++ b/src/core/types.h.ts
@@ -56,3 +56,5 @@ export const enum SignalType {
   error,
   complete
 }
+
+export type ArrayValues<TS extends any[]> = TS extends Array<infer T> ? T : void
diff --git a/src/helpers/debounce.ts b/src/helpers/debounce.ts
index 0191f0c..9ad248a 100644
--- a/src/helpers/debounce.ts
+++ b/src/helpers/debounce.ts
@@ -1,7 +1,7 @@
-export const debounce = <This = any>(wait: number, func: (this: This, ...args: any[]) => void) => {
+export const debounce = <TS extends any[]>(wait: number, func: (...args: TS) => void) => {
   let timeoutId: any = null
 
-  return function(this: This, ...args: any[]): void {
+  return function(this: any, ...args: TS): void {
     timeoutId > 0 && clearTimeout(timeoutId)
 
     timeoutId = setTimeout(() => {
diff --git a/src/helpers/throttle.ts b/src/helpers/throttle.ts
index 7b43ebf..acf2777 100644
--- a/src/helpers/throttle.ts
+++ b/src/helpers/throttle.ts
@@ -2,10 +2,10 @@
  * Creates a throttled function that only invokes func at most once per every `wait` milliseconds.
  * Function is called on the beginning of `wait` period.
  */
-export const throttle = <This = any>(wait: number, func: (this: This, ...args: any[]) => void) => {
+export const throttle = <TS extends any[]>(wait: number, func: (...args: TS) => void) => {
   let timeoutId: any
 
-  return function(this: This, ...args: any[]): void {
+  return function(this: any, ...args: TS): void {
     if (timeoutId) {
       return
     }
diff --git a/src/helpers/throttleEnd.ts b/src/helpers/throttleEnd.ts
index 0b8eee2..b676e8a 100644
--- a/src/helpers/throttleEnd.ts
+++ b/src/helpers/throttleEnd.ts
@@ -1,8 +1,8 @@
-export const throttleEnd = <This = any>(wait: number, fn: (this: This, ...args: any[]) => void) => {
-  let lastValues: any[] = []
+export const throttleEnd = <TS extends any[]>(wait: number, fn: (...args: TS) => void) => {
+  let lastValues: TS
   let timeout: any
 
-  return function(this: This, ...args: any[]): void {
+  return function(this: any, ...args: TS): void {
     lastValues = args
 
     if (timeout) {
diff --git a/src/helpers/types/concat.ts b/src/helpers/types/concat.ts
new file mode 100644
index 0000000..f01da39
--- /dev/null
+++ b/src/helpers/types/concat.ts
@@ -0,0 +1,123 @@
+// tslint:disable no-shadowed-variable
+// prettier-ignore
+export type Concat<AS extends any[], BS extends any[]> = AS extends [infer AA] ?
+  BS extends [infer BA] ? [AA, BA] :
+  BS extends [infer BA, infer BB] ? [AA, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB] ?
+  BS extends [infer BA] ? [AA, AB, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC] ?
+  BS extends [infer BA] ? [AA, AB, AC, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE, infer AF] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, AF, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, AF, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, AF, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE, infer AF, infer AG] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, AF, AG, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, AF, AG, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE, infer AF, infer AG, infer AH] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, AF, AG, AH, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE, infer AF, infer AG, infer AH, infer AI] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+AS extends [infer AA, infer AB, infer AC, infer AD, infer AE, infer AF, infer AG, infer AH, infer AI, infer AJ] ?
+  BS extends [infer BA] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA] :
+  BS extends [infer BA, infer BB] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB] :
+  BS extends [infer BA, infer BB, infer BC] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC] :
+  BS extends [infer BA, infer BB, infer BC, infer BD] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE, BF] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE, BF, BG] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE, BF, BG, BH] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE, BF, BG, BH, BI] :
+  BS extends [infer BA, infer BB, infer BC, infer BD, infer BE, infer BF, infer BG, infer BH, infer BI, infer BK] ? [AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, BA, BB, BC, BD, BE, BF, BG, BH, BI, BK] :
+  any[] :
+any[]
diff --git a/src/helpers/types/extractInnnerTypes.ts b/src/helpers/types/extractInnnerTypes.ts
new file mode 100644
index 0000000..2a68364
--- /dev/null
+++ b/src/helpers/types/extractInnnerTypes.ts
@@ -0,0 +1,82 @@
+// tslint:disable no-shadowed-variable
+import { Subscribable } from '../../core/types.h'
+
+export type ExtractInnerTypes<TS extends Array<Subscribable<any>>> = TS extends []
+  ? []
+  : TS extends [Subscribable<infer A>]
+    ? [A]
+    : TS extends [Subscribable<infer A>, Subscribable<infer B>]
+      ? [A, B]
+      : TS extends [Subscribable<infer A>, Subscribable<infer B>, Subscribable<infer C>]
+        ? [A, B, C]
+        : TS extends [
+            Subscribable<infer A>,
+            Subscribable<infer B>,
+            Subscribable<infer C>,
+            Subscribable<infer D>
+          ]
+          ? [A, B, C, D]
+          : TS extends [
+              Subscribable<infer A>,
+              Subscribable<infer B>,
+              Subscribable<infer C>,
+              Subscribable<infer D>,
+              Subscribable<infer E>
+            ]
+            ? [A, B, C, D, E]
+            : TS extends [
+                Subscribable<infer A>,
+                Subscribable<infer B>,
+                Subscribable<infer C>,
+                Subscribable<infer D>,
+                Subscribable<infer E>,
+                Subscribable<infer F>
+              ]
+              ? [A, B, C, D, E, F]
+              : TS extends [
+                  Subscribable<infer A>,
+                  Subscribable<infer B>,
+                  Subscribable<infer C>,
+                  Subscribable<infer D>,
+                  Subscribable<infer E>,
+                  Subscribable<infer F>,
+                  Subscribable<infer G>
+                ]
+                ? [A, B, C, D, E, F, G]
+                : TS extends [
+                    Subscribable<infer A>,
+                    Subscribable<infer B>,
+                    Subscribable<infer C>,
+                    Subscribable<infer D>,
+                    Subscribable<infer E>,
+                    Subscribable<infer F>,
+                    Subscribable<infer G>,
+                    Subscribable<infer H>
+                  ]
+                  ? [A, B, C, D, E, F, G, H]
+                  : TS extends [
+                      Subscribable<infer A>,
+                      Subscribable<infer B>,
+                      Subscribable<infer C>,
+                      Subscribable<infer D>,
+                      Subscribable<infer E>,
+                      Subscribable<infer F>,
+                      Subscribable<infer G>,
+                      Subscribable<infer H>,
+                      Subscribable<infer I>
+                    ]
+                    ? [A, B, C, D, E, F, G, H, I]
+                    : TS extends [
+                        Subscribable<infer A>,
+                        Subscribable<infer B>,
+                        Subscribable<infer C>,
+                        Subscribable<infer D>,
+                        Subscribable<infer E>,
+                        Subscribable<infer F>,
+                        Subscribable<infer G>,
+                        Subscribable<infer H>,
+                        Subscribable<infer I>,
+                        Subscribable<infer J>
+                      ]
+                      ? [A, B, C, D, E, F, G, H, I, J]
+                      : any[]
diff --git a/src/observable/combineLatest.ts b/src/observable/combineLatest.ts
index 4e35df4..329240c 100644
--- a/src/observable/combineLatest.ts
+++ b/src/observable/combineLatest.ts
@@ -2,23 +2,12 @@
 import { Observable } from '../core/Observable'
 import { Subscribable, Subscription } from '../core/types.h'
 import { getSpecies } from '../helpers/getSpecies'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 import { EMPTY } from './empty'
 
-// TODO: replace with spread after TS3.0 release
-export function combineLatest(): Observable<void>
-export function combineLatest<A>(s: Observable<A>): Observable<[A]>
-export function combineLatest<A, B>(sA: Observable<A>, sB: Observable<B>): Observable<[A, B]>
-export function combineLatest<A, B, C>(
-  sA: Observable<A>,
-  sB: Observable<B>,
-  sC: Observable<C>
-): Observable<[A, B, C]>
-export function combineLatest<A, B, C, D>(
-  sA: Observable<A>,
-  sB: Observable<B>,
-  sC: Observable<C>,
-  sD: Observable<D>
-): Observable<[A, B, C, D]>
+export function combineLatest<TS extends Array<Subscribable<any>>>(
+  ...streams: TS
+): Observable<ExtractInnerTypes<TS>>
 export function combineLatest(): Observable<any> {
   if (arguments.length < 1) {
     return EMPTY
diff --git a/src/observable/concat.ts b/src/observable/concat.ts
index 2d7835f..7d0104c 100644
--- a/src/observable/concat.ts
+++ b/src/observable/concat.ts
@@ -1,6 +1,7 @@
 import { Observable } from '../core/Observable'
-import { Subscribable, Subscription, SubscriptionObserver } from '../core/types.h'
+import { ArrayValues, Subscribable, Subscription, SubscriptionObserver } from '../core/types.h'
 import { getSpecies } from '../helpers/getSpecies'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 
 const subscribe = (
   streams: Array<Subscribable<any>>,
@@ -27,34 +28,9 @@ const subscribe = (
   })
 }
 
-export function concat<A>(arg1: Subscribable<A>): Observable<A>
-export function concat<A, B>(arg1: Subscribable<A>, arg2: Subscribable<B>): Observable<A | B>
-export function concat<A, B, C>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>
-): Observable<A | B | C>
-export function concat<A, B, C, D>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>
-): Observable<A | B | C | D>
-export function concat<A, B, C, D, E>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>
-): Observable<A | B | C | D | E>
-export function concat<A, B, C, D, E, F>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>,
-  arg6: Subscribable<F>
-): Observable<A | B | C | D | E | F>
+export function concat<TS extends Array<Subscribable<any>>>(
+  ...args: TS
+): Observable<ArrayValues<ExtractInnerTypes<TS>>>
 export function concat(): Observable<any> {
   const streams: Array<Subscribable<any>> = Array.prototype.slice.call(arguments)
   const C = getSpecies(streams[0])
diff --git a/src/observable/merge.ts b/src/observable/merge.ts
index f9a2f1b..4c70cc5 100644
--- a/src/observable/merge.ts
+++ b/src/observable/merge.ts
@@ -1,35 +1,11 @@
 import { Observable } from '../core/Observable'
-import { Subscribable } from '../core/types.h'
+import { ArrayValues, Subscribable } from '../core/types.h'
 import { getSpecies } from '../helpers/getSpecies'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 
-export function merge<A>(arg1: Subscribable<A>): Observable<A>
-export function merge<A, B>(arg1: Subscribable<A>, arg2: Subscribable<B>): Observable<A | B>
-export function merge<A, B, C>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>
-): Observable<A | B | C>
-export function merge<A, B, C, D>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>
-): Observable<A | B | C | D>
-export function merge<A, B, C, D, E>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>
-): Observable<A | B | C | D | E>
-export function merge<A, B, C, D, E, F>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>,
-  arg6: Subscribable<F>
-): Observable<A | B | C | D | E | F>
+export function merge<TS extends Array<Subscribable<any>>>(
+  ...streams: TS
+): Observable<ArrayValues<ExtractInnerTypes<TS>>>
 export function merge(): Observable<any> {
   const streams: Array<Subscribable<any>> = Array.prototype.slice.call(arguments)
   const C = getSpecies(streams[0])
diff --git a/src/observable/of.ts b/src/observable/of.ts
index 59f4d94..57fc79e 100644
--- a/src/observable/of.ts
+++ b/src/observable/of.ts
@@ -1,18 +1,7 @@
 import { Observable } from '../core/Observable'
+import { ArrayValues } from '../core/types.h'
 
-export function of<A>(a: A): Observable<A>
-export function of<A, B>(a: A, b: B): Observable<A | B>
-export function of<A, B, C>(a: A, b: B, c: C): Observable<A | B | C>
-export function of<A, B, C, D>(a: A, b: B, c: C, d: D): Observable<A | B | C | D>
-export function of<A, B, C, D, E>(a: A, b: B, c: C, d: D, e: E): Observable<A | B | C | D | E>
-export function of<A, B, C, D, E, F>(
-  a: A,
-  b: B,
-  c: C,
-  d: D,
-  e: E,
-  f: F
-): Observable<A | B | C | D | E | F>
+export function of<TS extends any[]>(...args: TS): Observable<ArrayValues<TS>>
 export function of(): Observable<any> {
   return Observable.of.apply(Observable, arguments)
 }
diff --git a/src/observable/startWith.ts b/src/observable/startWith.ts
index 3df29d9..3a896a4 100644
--- a/src/observable/startWith.ts
+++ b/src/observable/startWith.ts
@@ -1,31 +1,12 @@
 import { Observable } from '../core/Observable'
-import { Subscribable } from '../core/types.h'
+import { ArrayValues, Subscribable } from '../core/types.h'
 import { getSpecies } from '../helpers/getSpecies'
 import { concat } from './concat'
 
-export function startWith<A, T>(stream: Subscribable<T>, a: A): Observable<A | T>
-export function startWith<A, B, T>(stream: Subscribable<T>, a: A, b: B): Observable<A | B | T>
-export function startWith<A, B, C, T>(
+export function startWith<T, TS extends any[]>(
   stream: Subscribable<T>,
-  a: A,
-  b: B,
-  c: C
-): Observable<A | B | C | T>
-export function startWith<A, B, C, D, T>(
-  stream: Subscribable<T>,
-  a: A,
-  b: B,
-  c: C,
-  d: D
-): Observable<A | B | C | D | T>
-export function startWith<A, B, C, D, E, T>(
-  stream: Subscribable<T>,
-  a: A,
-  b: B,
-  c: C,
-  d: D,
-  e: E
-): Observable<A | B | C | D | E | T>
+  ...args: TS
+): Observable<ArrayValues<TS> | T>
 export function startWith(): Observable<any> {
   const input = Array.prototype.slice.call(arguments, 1)
   const stream = arguments[0]
diff --git a/src/operators/combineLatest.ts b/src/operators/combineLatest.ts
index caae2a2..8fed819 100644
--- a/src/operators/combineLatest.ts
+++ b/src/operators/combineLatest.ts
@@ -1,19 +1,15 @@
 import { Observable } from '../core/Observable'
-import { Subscribable, Unary } from '../core/types.h'
+import { Subscribable } from '../core/types.h'
+import { Concat } from '../helpers/types/concat'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 import { combineLatest as combineLatestObservable } from '../observable/combineLatest'
 
-export function combineLatest<A>(): Unary<Subscribable<A>, Observable<[A]>>
-export function combineLatest<A, B>(sA: Subscribable<A>): Unary<Subscribable<B>, Observable<[B, A]>>
-export function combineLatest<A, B, C>(
-  sA: Subscribable<A>,
-  sB: Subscribable<B>
-): Unary<Subscribable<C>, Observable<[C, A, B]>>
-export function combineLatest<A, B, C, D>(
-  sA: Subscribable<A>,
-  sB: Subscribable<B>,
-  sC: Subscribable<C>
-): Unary<Subscribable<C>, Observable<[D, A, B, C]>>
-export function combineLatest(...streams: Array<Subscribable<any>>) {
+export function combineLatest<TS extends Array<Subscribable<any>>>(
+  ...streams: TS
+): <T>(stream: Subscribable<T>) => Observable<Concat<[T], ExtractInnerTypes<TS>>>
+export function combineLatest() {
+  const streams: Array<Subscribable<any>> = Array.prototype.slice.call(arguments)
+
   return (stream: Subscribable<any>) => {
     const allStreams = [stream].concat(streams)
 
diff --git a/src/operators/concat.ts b/src/operators/concat.ts
index 3960ba0..de29307 100644
--- a/src/operators/concat.ts
+++ b/src/operators/concat.ts
@@ -1,34 +1,15 @@
 import { Observable } from '../core/Observable'
-import { Subscribable, Unary } from '../core/types.h'
+import { ArrayValues, Subscribable } from '../core/types.h'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 import { concat as concatObservable } from '../observable/concat'
 
-export function concat<T>(): Unary<Subscribable<T>, Subscribable<T>>
-export function concat<T, A>(arg1: Subscribable<A>): Unary<Subscribable<T>, Subscribable<T | A>>
-export function concat<T, A, B>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>
-): Unary<Subscribable<T>, Subscribable<T | A | B>>
-export function concat<T, A, B, C>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C>>
-export function concat<T, A, B, C, D>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C | D>>
-export function concat<T, A, B, C, D, E>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C | D | E>>
-export function concat(
-  ...streams: Array<Subscribable<any>>
-): Unary<Subscribable<any>, Observable<any>> {
+export function concat<TS extends Array<Subscribable<any>>>(
+  ...args: TS
+): <T>(stream: Subscribable<T>) => Observable<ArrayValues<ExtractInnerTypes<TS>> | T>
+
+export function concat() {
+  const streams: Array<Subscribable<any>> = Array.prototype.slice.call(arguments)
+
   return (stream: Subscribable<any>) => {
     const allStreams = [stream].concat(streams)
 
diff --git a/src/operators/merge.ts b/src/operators/merge.ts
index 2996b13..9c0ee9a 100644
--- a/src/operators/merge.ts
+++ b/src/operators/merge.ts
@@ -1,34 +1,14 @@
 import { Observable } from '../core/Observable'
-import { Subscribable, Unary } from '../core/types.h'
+import { ArrayValues, Subscribable } from '../core/types.h'
+import { ExtractInnerTypes } from '../helpers/types/extractInnnerTypes'
 import { merge as mergeObservable } from '../observable/merge'
 
-export function merge<T>(): Unary<Subscribable<T>, Subscribable<T>>
-export function merge<T, A>(arg1: Subscribable<A>): Unary<Subscribable<T>, Subscribable<T | A>>
-export function merge<T, A, B>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>
-): Unary<Subscribable<T>, Subscribable<T | A | B>>
-export function merge<T, A, B, C>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C>>
-export function merge<T, A, B, C, D>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C | D>>
-export function merge<T, A, B, C, D, E>(
-  arg1: Subscribable<A>,
-  arg2: Subscribable<B>,
-  arg3: Subscribable<C>,
-  arg4: Subscribable<D>,
-  arg5: Subscribable<E>
-): Unary<Subscribable<T>, Subscribable<T | A | B | C | D | E>>
-export function merge(
-  ...streams: Array<Subscribable<any>>
-): Unary<Subscribable<any>, Observable<any>> {
+export function merge<TS extends Array<Subscribable<any>>>(
+  ...streams: TS
+): <T>(stream: Subscribable<T>) => Observable<T | ArrayValues<ExtractInnerTypes<TS>>>
+export function merge() {
+  const streams: Array<Subscribable<any>> = Array.prototype.slice.call(arguments)
+
   return (stream: Subscribable<any>) => {
     const allStreams = [stream].concat(streams)
 
diff --git a/src/operators/startWith.ts b/src/operators/startWith.ts
index a4a5ae7..ed6d749 100644
--- a/src/operators/startWith.ts
+++ b/src/operators/startWith.ts
@@ -1,27 +1,10 @@
 import { Observable } from '../core/Observable'
-import { Subscribable } from '../core/types.h'
+import { ArrayValues, Subscribable } from '../core/types.h'
 import { startWith as startWithObservable } from '../observable/startWith'
 
-export function startWith<A>(a: A): <T>(stream: Subscribable<T>) => Observable<A | T>
-export function startWith<A, B>(a: A, b: B): <T>(stream: Subscribable<T>) => Observable<A | B | T>
-export function startWith<A, B, C>(
-  a: A,
-  b: B,
-  c: C
-): <T>(stream: Subscribable<T>) => Observable<A | B | C | T>
-export function startWith<A, B, C, D>(
-  a: A,
-  b: B,
-  c: C,
-  d: D
-): <T>(stream: Subscribable<T>) => Observable<A | B | C | D | T>
-export function startWith<A, B, C, D, E>(
-  a: A,
-  b: B,
-  c: C,
-  d: D,
-  e: E
-): <T>(stream: Subscribable<T>) => Observable<A | B | C | D | E | T>
+export function startWith<TS extends any[]>(
+  ...args: TS
+): <T>(stream: Subscribable<T>) => Observable<ArrayValues<TS> | T>
 export function startWith() {
   const input = Array.prototype.slice.call(arguments)