Combine comparison and other info

Author: freak4pc

Documentation/ComparisonWithOtherLibraries.md

@@ -1,4 +1,20 @@
-## Comparison with ReactiveSwift
+# Comparison with other libraries
+
+This section attempts to compare RxSwift with other known and popular alternatives.
+
+The best part about reactive programming is that most of the concepts you'll learn from either of these frameworks are entirely applicable to RxSwift, and vice-versa, with only relatively minor framework-specific concepts and naming conventions.
+
+## Apple's Combine
+
+Combine is Apple's own implementation of the [Reactive Streams](https://www.reactive-streams.org) standard. The main differences to consider are that Combine uses typed errors, and supports backpressure. Its huge downside is  that it's closed source, limited to iOS 13 and up, and does not support Linux as of today.
+
+It also does not have its own testing framework like RxTest or RxBlocking, and doesn't have its own UIKit-supporting framework such as RxCocoa, since it is more aimed towards SwiftUI. Some of these issues have been addressed by community projects such as [CombineCocoa](https://github.com/CombineCommunity/CombineCocoa), [combine-schedulers](https://github.com/pointfreeco/combine-schedulers) and [CombineExpectations](https://github.com/groue/CombineExpectations).
+
+It is also (as of 2020) a relatively young and not as battle-tested as RxSwift or ReactiveSwift which are around for over half a decade.
+
+If you're interested in using Combine for your relatively modern codebase while still using your RxSwift codebase, you can leverage [RxCombine](https://github.com/CombineCommunity/RxCombine), a community project which aims to provide interoperatbility between Combine and RxSwift.
+
+## ReactiveSwift
 
 RxSwift is somewhat similar to ReactiveSwift since ReactiveSwift borrows a large number of concepts from Rx.
 

README.md

@@ -54,7 +54,7 @@ KVO observation, async operations, UI Events and other streams of data are all u
 
 ###### ... compare
 
-* [with other libraries](Documentation/ComparisonWithOtherLibraries.md).
+* [with Combine and ReactiveSwift](Documentation/ComparisonWithOtherLibraries.md).
 
 ###### ... understand the structure
 

Tests/RxSwiftTests/Observable+JustTests.swift

@@ -16,9 +16,7 @@ class ObservableJustTest : RxTest {
 extension ObservableJustTest {
     func testJust_Immediate() {
         let scheduler = TestScheduler(initialClock: 0)
-        
-        let totalPrice: Observable<Decimal>
-        
+
         let res = scheduler.start {
             return Observable.just(42)
         }