System.Collections.Immutable 9.0.0-rc.2.24473.5

About

This package provides collections that are thread safe and guaranteed to never change their contents, also known as immutable collections. Like strings, any methods that perform modifications will not change the existing instance but instead return a new instance. For efficiency reasons, the implementation uses a sharing mechanism to ensure that newly created instances share as much data as possible with the previous instance while ensuring that operations have a predictable time complexity.

The System.Collections.Immutable library is built-in as part of the shared framework in .NET Runtime. The package can be installed when you need to use it in other target frameworks.

How to Use

using System.Collections.Immutable;

// Create immutable set of strings
ImmutableHashSet<string> colors = ImmutableHashSet.Create("Red", "Green", "Blue");

// Create a new set by adding and removing items from the original set
ImmutableHashSet<string> colorsModified = colors.Remove("Red").Add("Orange");

foreach (string s in colorsModified)
{
    Console.WriteLine(s);
}

/* Example output:
 Blue
 Green
 Orange
 */

Main Types

The main types provided by this library are:

  • System.Collections.Immutable.ImmutableArray
  • System.Collections.Immutable.ImmutableArray<T>
  • System.Collections.Immutable.ImmutableDictionary
  • System.Collections.Immutable.ImmutableDictionary<TKey,TValue>
  • System.Collections.Immutable.ImmutableHashSet
  • System.Collections.Immutable.ImmutableHashSet<T>
  • System.Collections.Immutable.ImmutableList
  • System.Collections.Immutable.ImmutableList<T>
  • System.Collections.Immutable.ImmutableQueue
  • System.Collections.Immutable.ImmutableQueue<T>
  • System.Collections.Immutable.ImmutableSortedDictionary
  • System.Collections.Immutable.ImmutableSortedDictionary<TKey,TValue>
  • System.Collections.Immutable.ImmutableSortedSet
  • System.Collections.Immutable.ImmutableSortedSet<T>
  • System.Collections.Immutable.ImmutableStack
  • System.Collections.Immutable.ImmutableStack<T>
  • System.Collections.Frozen.FrozenDictionary
  • System.Collections.Frozen.FrozenDictionary<TKey, TValue>
  • System.Collections.Frozen.FrozenSet
  • System.Collections.Frozen.FrozenSet<T>

Additional Documentation

Feedback & Contributing

System.Collections.Immutable is released as open source under the MIT license. Bug reports and contributions are welcome at the GitHub repository.

Showing the top 20 packages that depend on System.Collections.Immutable.

Packages Downloads
protobuf-net.Core
Provides simple access to fast and efficient "Protocol Buffers" serialization from .NET applications
3
Microsoft.Orleans.Core
Core library of Microsoft Orleans used both on the client and server.
3
Microsoft.CodeAnalysis.Scripting.Common
Microsoft .NET Compiler Platform ("Roslyn") shared scripting package. Do not install this package manually, it will be added as a prerequisite by other packages that require it.
3
Microsoft.Orleans.Reminders.AzureStorage
Microsoft Orleans reminders provider backed by Azure Table Storage
3
Npgsql
Npgsql is the open source .NET data provider for PostgreSQL.
3
Microsoft.CodeAnalysis.CSharp.Workspaces
.NET Compiler Platform ("Roslyn") support for analyzing C# projects and solutions. More details at https://aka.ms/roslyn-packages This package was built from the source at https://github.com/dotnet/roslyn/commit/e68227ea677b76a3c603bd616f03ea6d952b2458.
3
Microsoft.CodeAnalysis.AnalyzerUtilities
Analyzer utilities for various analyses, including Dataflow analysis based on ControlFlowGraph API in Microsoft.CodeAnalysis. More details at https://aka.ms/roslyn-packages This package was built from the source at https://github.com/dotnet/dotnet/commit/ddf39a1b4690fbe23aea79c78da67004a5c31094.
3
EmptyFiles
A collection of minimal binary files.
3
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
3
OpenTelemetry
OpenTelemetry .NET SDK
3
Microsoft.Orleans.Core
Core library of Microsoft Orleans used both on the client and server.
2
SixLabors.Fonts
A cross-platform library for loading and laying out for processing and measuring; written in C#
2

https://go.microsoft.com/fwlink/?LinkID=799421

.NET Framework 4.6.2

.NET 8.0

  • No dependencies.

.NET 9.0

  • No dependencies.

.NET Standard 2.0

Version Downloads Last updated
10.0.0-preview.5.25277.114 2 6/11/2025
10.0.0-preview.4.25258.110 0 5/12/2025
10.0.0-preview.3.25171.5 1 6/11/2025
10.0.0-preview.2.25163.2 2 6/11/2025
10.0.0-preview.1.25080.5 2 6/11/2025
9.0.6 1 6/13/2025
9.0.5 0 5/13/2025
9.0.4 0 4/8/2025
9.0.3 0 3/11/2025
9.0.2 0 2/11/2025
9.0.1 1 6/10/2025
9.0.0 0 11/12/2024
9.0.0-rc.2.24473.5 1 6/12/2025
9.0.0-rc.1.24431.7 1 6/11/2025
9.0.0-preview.7.24405.7 2 6/7/2025
9.0.0-preview.6.24327.7 1 6/12/2025
9.0.0-preview.5.24306.7 1 6/12/2025
9.0.0-preview.4.24266.19 0 5/21/2024
9.0.0-preview.3.24172.9 1 6/11/2025
9.0.0-preview.2.24128.5 1 6/11/2025
9.0.0-preview.1.24080.9 1 6/11/2025
8.0.0 0 11/14/2023
8.0.0-rc.2.23479.6 1 6/11/2025
8.0.0-rc.1.23419.4 1 6/11/2025
8.0.0-preview.7.23375.6 1 6/12/2025
8.0.0-preview.6.23329.7 2 6/11/2025
8.0.0-preview.5.23280.8 1 6/11/2025
8.0.0-preview.4.23259.5 1 6/12/2025
8.0.0-preview.3.23174.8 1 6/11/2025
8.0.0-preview.2.23128.3 1 6/11/2025
8.0.0-preview.1.23110.8 1 6/11/2025
7.0.0 1 6/10/2025
7.0.0-rc.2.22472.3 1 6/12/2025
7.0.0-rc.1.22426.10 1 6/13/2025
7.0.0-preview.7.22375.6 1 6/12/2025
7.0.0-preview.6.22324.4 1 6/11/2025
7.0.0-preview.5.22301.12 2 6/11/2025
7.0.0-preview.4.22229.4 1 6/11/2025
7.0.0-preview.3.22175.4 1 6/11/2025
7.0.0-preview.2.22152.2 2 6/11/2025
7.0.0-preview.1.22076.8 2 6/11/2025
6.0.1 1 6/10/2025
6.0.0 1 6/10/2025
6.0.0-rc.2.21480.5 1 6/12/2025
6.0.0-rc.1.21451.13 2 6/9/2025
6.0.0-preview.7.21377.19 1 6/11/2025
6.0.0-preview.6.21352.12 2 6/9/2025
6.0.0-preview.5.21301.5 1 6/11/2025
6.0.0-preview.4.21253.7 1 6/11/2025
6.0.0-preview.3.21201.4 1 6/11/2025
6.0.0-preview.2.21154.6 1 6/12/2025
6.0.0-preview.1.21102.12 1 6/11/2025
5.0.0 0 11/9/2020
5.0.0-rc.2.20475.5 2 6/8/2025
5.0.0-rc.1.20451.14 1 6/12/2025
5.0.0-preview.8.20407.11 1 6/11/2025
5.0.0-preview.7.20364.11 1 6/11/2025
5.0.0-preview.6.20305.6 1 6/11/2025
5.0.0-preview.5.20278.1 1 6/11/2025
5.0.0-preview.4.20251.6 2 6/11/2025
5.0.0-preview.3.20214.6 1 6/11/2025
5.0.0-preview.2.20160.6 2 6/11/2025
5.0.0-preview.1.20120.5 1 6/11/2025
1.7.1 0 5/12/2020
1.7.0 1 6/8/2025
1.7.0-preview3.19551.4 1 6/11/2025
1.7.0-preview2.19523.17 1 6/11/2025
1.7.0-preview1.19504.10 1 6/11/2025
1.6.0 0 9/23/2019
1.6.0-rc1.19456.4 1 6/11/2025
1.6.0-preview9.19421.4 1 6/11/2025
1.6.0-preview9.19416.11 1 6/11/2025
1.6.0-preview8.19405.3 1 6/11/2025
1.6.0-preview7.19362.9 1 6/12/2025
1.6.0-preview6.19303.8 1 6/12/2025
1.6.0-preview6.19264.9 1 6/11/2025
1.6.0-preview5.19224.8 2 6/11/2025
1.6.0-preview4.19212.13 1 6/11/2025
1.6.0-preview3.19128.7 1 6/11/2025
1.6.0-preview.19073.11 1 6/11/2025
1.6.0-preview.18571.3 1 6/11/2025
1.5.0 0 5/29/2018
1.5.0-rc1 2 6/10/2025
1.5.0-preview2-26406-04 1 6/11/2025
1.5.0-preview1-26216-02 2 6/10/2025
1.4.0 0 8/11/2017
1.4.0-preview2-25405-01 1 6/11/2025
1.4.0-preview1-25305-02 1 6/11/2025
1.3.1 3 6/8/2025
1.3.0 1 6/10/2025
1.3.0-preview1-24530-04 1 6/11/2025
1.2.0 0 6/27/2016
1.2.0-rc2-24027 1 6/11/2025
1.1.38-beta-23516 1 6/11/2025
1.1.38-beta-23409 1 6/11/2025
1.1.38-beta-23225 1 6/11/2025
1.1.37 0 7/29/2015
1.1.37-beta-23109 1 6/11/2025
1.1.37-beta-23019 1 6/11/2025
1.1.36 0 5/11/2015
1.1.34-rc 0 3/6/2015
1.1.33-beta 0 12/10/2014
1.1.32-beta 2 6/10/2025