Allow creating a Single from async closure

Author: freak4pc

Documentation/SwiftConcurrency.md

@@ -63,3 +63,17 @@ stream.asObservable()
         onError: { ... }
     )
 ```
+
+### Wrapping an `async` result as a `Single`
+
+If you already have an async piece of work that returns a single result you wish to await, you can bridge it back to the Rx wordl by using `Single.create`, a special overload which takes an `async throws` closure where you can simply await your async work:
+
+```swift
+func doIncredibleWork() async throws -> AmazingRespones {
+    ...
+}
+
+let single = Single.create {
+    try await doIncredibleWork()
+} // Single<AmazingResponse>
+```

Rx.xcodeproj/project.pbxproj

@@ -1071,7 +1071,7 @@
 		C8093CBF1B8A72BE0088E94D /* PublishSubject.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; lineEnding = 0; path = PublishSubject.swift; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.swift; };
 		C8093CC01B8A72BE0088E94D /* ReplaySubject.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; lineEnding = 0; path = ReplaySubject.swift; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.swift; };
 		C8093CC11B8A72BE0088E94D /* SubjectType.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SubjectType.swift; sourceTree = "<group>"; };
-		C8093E8B1B8A732E0088E94D /* DelegateProxy.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; lineEnding = 0; path = DelegateProxy.swift; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.swift; };
+		C8093E8B1B8A732E0088E94D /* DelegateProxy.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; lineEnding = 0; path = DelegateProxy.swift; sourceTree = "<group>"; };
 		C8093E8C1B8A732E0088E94D /* DelegateProxyType.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DelegateProxyType.swift; sourceTree = "<group>"; };
 		C8093E9C1B8A732E0088E94D /* RxTarget.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RxTarget.swift; sourceTree = "<group>"; };
 		C8093E9D1B8A732E0088E94D /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };

RxSwift/Traits/PrimitiveSequence/PrimitiveSequence+Concurrency.swift

@@ -11,6 +11,38 @@ import Foundation
 #if swift(>=5.6) && canImport(_Concurrency) && !os(Linux)
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public extension PrimitiveSequenceType where Trait == SingleTrait {
+    /**
+     Creates an `Single` from the result of an asynchronous operation
+
+     - seealso: [create operator on reactivex.io](http://reactivex.io/documentation/operators/create.html)
+
+     - parameter work: An `async` closure expected to return an element of type `Element`
+
+     - returns: A `Single` of the `async` closure's element type
+     */
+    @_disfavoredOverload
+    static func create(
+        detached: Bool = false,
+        priority: TaskPriority? = nil,
+        work: @Sendable @escaping () async throws -> Element
+    ) -> PrimitiveSequence<Trait, Element> {
+        .create { single in
+            let operation: () async throws -> Void = {
+                await single(
+                    Result { try await work() }
+                )
+            }
+
+            let task = if detached {
+                Task.detached(priority: priority, operation: operation)
+            } else {
+                Task(priority: priority, operation: operation)
+            }
+
+            return Disposables.create { task.cancel() }
+        }
+    }
+    
     /// Allows awaiting the success or failure of this `Single`
     /// asynchronously via Swift's concurrency features (`async/await`)
     ///
@@ -161,4 +193,16 @@ public extension PrimitiveSequenceType where Trait == CompletableTrait, Element
         }
     }
 }
+
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+extension Result where Failure == Swift.Error {
+    @_disfavoredOverload
+    init(catching body: () async throws -> Success) async {
+        do {
+            self = try await .success(body())
+        } catch {
+            self = .failure(error)
+        }
+    }
+}
 #endif

Tests/RxSwiftTests/PrimitiveSequence+ConcurrencyTests.swift

@@ -11,6 +11,7 @@ import Dispatch
 import RxSwift
 import XCTest
 import RxTest
+import RxBlocking
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 class PrimitiveSequenceConcurrencyTests: RxTest {
@@ -72,6 +73,19 @@ extension PrimitiveSequenceConcurrencyTests {
         task.cancel()
     }
 
+    func testCreateSingleFromAsync() {
+        let randomResult = Int.random(in: 100...100000)
+        let work: () async throws -> Int = { randomResult }
+
+        let single = Single.create {
+            try await work()
+        }
+
+        XCTAssertEqual(
+            try! single.toBlocking().toArray(),
+            [randomResult]
+        )
+    }
 }
 
 // MARK: - Maybe