Adding Cast and OfType.

AsyncRx.NET/System.Reactive.Async/System/Reactive/Linq/Operators/Cast.cs

@@ -0,0 +1,28 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+namespace System.Reactive.Linq
+{
+    partial class AsyncObservable
+    {
+        public static IAsyncObservable<TResult> Cast<TSource, TResult>(this IAsyncObservable<TSource> source)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+
+            return Create<TResult>(observer => source.SubscribeAsync(AsyncObserver.Cast<TSource, TResult>(observer)));
+        }
+    }
+
+    partial class AsyncObserver
+    {
+        public static IAsyncObserver<TSource> Cast<TSource, TResult>(this IAsyncObserver<TResult> observer)
+        {
+            if (observer == null)
+                throw new ArgumentNullException(nameof(observer));
+
+            return Select<TSource, TResult>(observer, x => (TResult)(object)x);
+        }
+    }
+}

AsyncRx.NET/System.Reactive.Async/System/Reactive/Linq/Operators/OfType.cs

@@ -0,0 +1,28 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+namespace System.Reactive.Linq
+{
+    partial class AsyncObservable
+    {
+        public static IAsyncObservable<TResult> OfType<TSource, TResult>(this IAsyncObservable<TSource> source)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+
+            return Create<TResult>(observer => source.SubscribeAsync(AsyncObserver.OfType<TSource, TResult>(observer)));
+        }
+    }
+
+    partial class AsyncObserver
+    {
+        public static IAsyncObserver<TSource> OfType<TSource, TResult>(this IAsyncObserver<TResult> observer)
+        {
+            if (observer == null)
+                throw new ArgumentNullException(nameof(observer));
+
+            return Where(Select<TSource, TResult>(observer, x => (TResult)(object)x), x => x is TResult);
+        }
+    }
+}