Awaiting OptionAsync / EitherAsync

[BrunoJuchli]

EitherAsync

In contrast to OptionAsync<A>, EitherAsync<L,R> can't be await because it's missing the AsyncMethodBuilderAttribute -- well it's actually commented out as can be seen here:

language-ext/LanguageExt.Core/Monads/Alternative Value Monads/Either/EitherAsync/EitherAsync.cs

Line 35 in d5248b6

//[AsyncMethodBuilder(typeof(EitherAsyncBuilder<,>))]

Is there a plan to add that later on? Are there significant obstacles to doing so or would a PR be accepted?
(I'd expect awaiting an EitherAsync<L,R> to return an Either<L,R>).

OptionAsync

Why does awaiting an OptionAsync<A> return A? and not Option<A>?

The questions arose in the context of a unit test, like:

 var result = await testee.DoSomething(); // DoSomething has a signature return-type of OptionAsync<A>()
 
 result.Should().BeNone(); // doesn't work because it's null

Now for the test it doesn't matter that much, I can usually just test for null instead -- i still don't like it very much because IMO it's confusing to work with null when explicitly trying to go the extra mile to work funtional style.
So what I do is I add a .ToOption() after the call to DoSomething(). I'd rather expected it to be vice-versa: requiring an extra call like "ToNullable()" to have it return a Task<A?>.
Maybe there's a good reason for the current behavior and someone can shed some light on it? Always happy to learn :-)

[fjmorel]

I forgot to check discussions before writing up #1019

You can await an EitherAsync, but you can't use it as the return type of an async method yet, because of the commented out line you pointed out.

edit: copying link to an issue which explains the async/await limitation: dotnet/csharplang#3723