Optimizing All and Any.

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

@@ -38,7 +38,34 @@ namespace System.Reactive.Linq
             if (predicate == null)
                 throw new ArgumentNullException(nameof(predicate));
 
-            return All<TSource>(observer, x => Task.FromResult(predicate(x)));
+            return Create<TSource>(
+                async x =>
+                {
+                    var b = default(bool);
+
+                    try
+                    {
+                        b = predicate(x);
+                    }
+                    catch (Exception ex)
+                    {
+                        await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                        return;
+                    }
+
+                    if (!b)
+                    {
+                        await observer.OnNextAsync(false).ConfigureAwait(false);
+                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                    }
+                },
+                observer.OnErrorAsync,
+                async () =>
+                {
+                    await observer.OnNextAsync(true).ConfigureAwait(false);
+                    await observer.OnCompletedAsync().ConfigureAwait(false);
+                }
+            );
         }
 
         public static IAsyncObserver<TSource> All<TSource>(IAsyncObserver<bool> observer, Func<TSource, Task<bool>> predicate)

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

@@ -66,7 +66,34 @@ namespace System.Reactive.Linq
             if (predicate == null)
                 throw new ArgumentNullException(nameof(predicate));
 
-            return Any<TSource>(observer, x => Task.FromResult(predicate(x)));
+            return Create<TSource>(
+                async x =>
+                {
+                    var b = default(bool);
+
+                    try
+                    {
+                        b = predicate(x);
+                    }
+                    catch (Exception ex)
+                    {
+                        await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                        return;
+                    }
+
+                    if (b)
+                    {
+                        await observer.OnNextAsync(true).ConfigureAwait(false);
+                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                    }
+                },
+                observer.OnErrorAsync,
+                async () =>
+                {
+                    await observer.OnNextAsync(false).ConfigureAwait(false);
+                    await observer.OnCompletedAsync().ConfigureAwait(false);
+                }
+            );
         }
 
         public static IAsyncObserver<TSource> Any<TSource>(IAsyncObserver<bool> observer, Func<TSource, Task<bool>> predicate)