System.Collections

This is the assembly that generally surfaces generic collections such as List<T> and PriorityQueue<TElement, TPriority>.

Generic collection interfaces that are used by lower-level parts of the framework, such as IList<T> and IAsyncEnumerable<T> are surfaced by the System.Runtime assembly. The implementations for these collections live in System.Private.CoreLib.

Documentation can be found at https://learn.microsoft.com/dotnet/csharp/programming-guide/concepts/collections.

Contribution Bar

• We consider new features, new APIs and performance changes
• We consider PRs that target this library for new source code analyzers
• We don't accept refactoring changes due to new language features

Although a lot of the types are mature, the code base continues to evolve for better performance and to keep up with runtime enhancements.

See the Help Wanted issues.

Deployment

System.Collections is included in the shared framework and also provided as a NuGet package.