feat: add last() to async sequence (#36)

Asynchrone/Source/Extensions/AsyncSequence+Extension.swift

@@ -50,6 +50,16 @@ extension AsyncSequence {
         }
     }
 
+    /// The last element of the sequence, if there is one.
+    public func last() async rethrows -> Element? {
+        var latestElement: Element?
+        for try await element in self {
+            latestElement = element
+        }
+
+        return latestElement
+    }
+
     /// Collect elements from a sequence.
     ///
     /// ```swift

AsynchroneTests/Tests/Extensions/AsyncSequenceTests.swift

@@ -28,8 +28,15 @@ final class AsyncSequenceTests: XCTestCase {
     // MARK: First
 
     func testFirst() async {
-        let firstValue = await self.sequence.first()
-        XCTAssertEqual(firstValue, 1)
+        let element = await self.sequence.first()
+        XCTAssertEqual(element, 1)
+    }
+
+    // MARK: Last
+
+    func testLast() async {
+        let element = await self.sequence.last()
+        XCTAssertEqual(element, 3)
     }
 
     // MARK: Collect

README.md

@@ -71,6 +71,22 @@ print(await sequence.first())
 // 1
 ```
 
+#### Last
+
+```swift
+let sequence = AsyncStream<Int> { continuation in
+    continuation.yield(1)
+    continuation.yield(2)
+    continuation.yield(3)
+    continuation.finish()
+}
+
+print(await sequence.last())
+
+// Prints:
+// 3
+```
+
 #### Collect
 
 ```swift