ReadOnlySet<T> is coming in .NET 9

ReadOnlySet is coming in .NET 9

Say goodbye to issues with IReadOnlySet interface. No more casting back to mutable sets or creating custom read-only sets!

The latest Preview 6 version brings this new type.

I often prefer ISet above IList in Domain Driven Design.

Why? Because they guarantee unique elements in the collection.

It is often a requirement to prevent duplicate elements and ISet is perfect for this. Also, it comes with some nice methods to compare, merge, and create Subsets.