Which .NET library has copy-on-write collections?

Question

I am searching for .NET copy-on-write collections to use in C# programs, such as List, Dictionary, etc. Which collections have that property?

Answer 1

Include the reference FSharp.Core. And then you have access to many kinds of collections which is immutable (Set, List, Map etc.)

These are located in Microsoft.FSharp.Collections.

Example:

var map = MapModule.Empty<string, int>(); var newMap = map.Add("key", 1); 

You probably want to define some extension methods so you can call directly on map.

Update: The BCL team is working on immutable collections as mentioned in the other answer which makes this partly obsolete. F# collections can still be used, but BCL collections have a more C# feel to them.

Direct link to Nuget package: Immutable Collections

Answer 2

.NET just shipped their first copy-on-write collections, which I suggest you try out.