Optional VS NullGuard

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.

Nullable reference types + https://github.com/Fody/NullGuard

I find Nullable Reference Types combined with NullGuard to be pretty good.

For example here from the readme I can exactly see what boilerplate is generated for me.

Some tools can help to enforce this convention like ReSharper and NullGuard. I guess, although I haven’t tried this yet, you can add a custom rule to SonarQube which will alert when the word null appears.