Enumerables | created multiple methods from the enumerable module

My aim is to get the display name attribute from my enumerables so that I can display their values on an index page without having strange formatting and instead clear, readable lines.

My enumerables look like this:

The first function is designed to enable linq to execute lambda functions safely in parallel (even the async void ones).

So you can do collection.AsParallel().ForAllASync(async x => await x.Action).

The second function is designed to enable you to combine and execute multiple IAsyncEnumerables in parallel and return their results as quick as possible.

I have the following code:

The first function is designed to enable linq to execute lambda functions safely in parallel (even the async void ones).

So you can do collection.AsParallel().ForAllASync(async x => await x.Action).

The second function is designed to enable you to combine and execute multiple IAsyncEnumerables in parallel and return their results as quick as possible.

I have the following code:

For performance reasons many of my services are returning IQueryables right now, so the caller can decide what elements to filter before they get materialized. For design reasons (interfaces etc.) I'd rather like to return IEnumerables but that sure removes the advantages of IQueryables: materialization of the complete result set plus no -Async methods.

I've started writing some extension methods that prefer IQueryable over IEnumerable, e.g.:

C# 8 now has IAsyncEnumerable. Is there a Kotlin equivalent to this? For instance, in C# you can await foreach(...) now (with IAsyncEnumerable):

I have a List of lists i.e. IList>, I need to sort by property DisplayOrder.

I have a rubocop problem while doing my own ruby enumerables. I used a === and rubocop is asking me to change it. But every time I try to put something different my method stops working as desired.

Count() scans through all element, hence if (list.Count() == 1)will not perform well if enumerable contains a lot of elements.

Single() throws exception if there are not exactly one elements. Using try { list.Single(); } catch(InvalidOperationException e) {} is clumsy and inefficient.

SingleOrDefault() throws exception if there are more than one elements, hence if (list.SingleOrDefault() == null) (assuming TSource is of reference type) will not work for enumerables of size greater than one.

I am using Dapper to stream data from a very large set in SQL Server. It works fine with returning IEnumerable and calling Query(), but when I switch to QueryAsync(), it seems that the program tries to read all of the data from SQL Server instead of streaming.

According to this question, it should work fine with buffered: false, which I am doing, but the question says nothing about async/await.

Now according to this question, it's not straightforward to do what I want with QueryAsync().

Do I understand correctly that enumerables are iterated when the context is switched for async/await?

Another question if this is something that will be possible to do when the new C#8 async streaming is available?