MoreLINQ VS Optional

You can grab MoreLinq off of Nuget for pre-.NET6 and it has a DistinctBy implementation that you might be able to use: https://github.com/morelinq/MoreLINQ

Install "morelinq" 3.3.2 from Nuget: https://www.nuget.org/packages/morelinq You know you got the right one if it has about 37.2 million downloads.

If you don't already know about it, I highly recommend checking out the MoreLINQ open source project which adds a bunch of these less common but still occasionally useful extensions to LINQ. They also include an Index method which does exactly what your WithIndex method does, yielding out KeyValuePair entries for each iteration.

yield return is a significant core piece of the framework. It's the basis of which most deferred execution and LINQ is built upon and any extension one would want to add to LINQ. (for example)

For a time, I'd say the Query Syntax was comparatively as popular as the Method Syntax. But over the years as LINQ became ubiquitous for working with non-database queries (LINQ-to-Objects) and more users extended them (for example, MoreLinq) the Method Syntax became more popular. I'd say nowadays the Query Syntax is relatively rare to see and perhaps mostly limited to direct database queries or these scenarios like "join" that are easier.

I suggest morelinq https://github.com/morelinq/MoreLINQ

If you don't already know about it, take a gander at the MoreLINQ extensions. I don't think it solves this particular problem, but it's a great example of extending LINQ.

It's part of the MoreLinq library. The Window() function code is here.

Since then C# introduced nullable which takes away some of the needs for a Option type. So what is your opionion? Do libraries like Optional still have a place when nullable is enabled?

Optional is my go-to for c# (you could also use the F# Option of course but pulling fsharp.core into a C# project tends to raise eyebrows in my experience)

This library provides similar functionality to F#'s Option type. I can't vouch for it, but it's there.

Not really. C# doesn't have monads but you can easily add something like https://github.com/nlkl/Optional which is great for a team familiar with option types and IMO will lead to a more productive team with a more concise code base.

You can use Optional

The option type is a different way to represent an optional value. This type asks if a value exists and, if so, accesses the value. When trying to access the value which doesn’t exist, it raises an exception. This solves the problem of NullPointerException raised in code areas away from the bug. In Java there is the Optional class. In C# (until C# 7 ) there is the Nullable type which is only for value types but you can create your own or use a library.