System.Collections.Immutable 9.0.1

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
Microsoft.NETCore
Provides a set of packages that can be used when building portable libraries on .NETCore based platforms. \r\n TFS ID: 1599443, GitHub SHA: https://github.com/dotnet/corefx/tree/eede273a4dfabcea608621f5e1bbf8ad00584cfb
193
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
176
Microsoft.VisualStudio.Debugger.Contracts
Package containing extensibility contracts between the debugger and other Visual Studio components, such as language services.
173
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
159
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
154
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
153
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
152
System.Diagnostics.StackTrace
Provides the System.Diagnostics.StackTrace class, which allows interaction with local and remote processes. Commonly Used Types: System.Diagnostics.StackFrame System.Diagnostics.StackTrace When using NuGet 3.x this package requires at least version 3.4.
145
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
144
Microsoft.Build.Tasks.Core
This package contains the Microsoft.Build.Tasks assembly which implements the commonly used tasks of MSBuild.
144
Microsoft.Build.Tasks.Core
This package contains the Microsoft.Build.Tasks assembly which implements the commonly used tasks of MSBuild.
143
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
143
Microsoft.Build.Utilities.Core
This package contains the Microsoft.Build.Utilities assembly which is used to implement custom MSBuild tasks.
142
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
142
Microsoft.VisualStudio.Web.CodeGeneration.Contracts
Contains interfaces for Project Model and messaging for scaffolding.
141
Microsoft.EntityFrameworkCore
Entity Framework Core is a modern object-database mapper for .NET. It supports LINQ queries, change tracking, updates, and schema migrations. EF Core works with SQL Server, Azure SQL Database, SQLite, Azure Cosmos DB, MySQL, PostgreSQL, and other databases through a provider plugin API. Commonly Used Types: Microsoft.EntityFrameworkCore.DbContext Microsoft.EntityFrameworkCore.DbSet
140
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
140
Microsoft.VisualStudio.Web.CodeGeneration.Contracts
Contains interfaces for Project Model and messaging for scaffolding.
139
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
139

.NET Framework 4.6.2

.NET 8.0

  • No dependencies.

.NET 9.0

  • No dependencies.

.NET Standard 2.0

Version Downloads Last updated
10.0.1 13 12/10/2025
10.0.0 29 11/12/2025
10.0.0-rc.2.25502.107 37 10/15/2025
10.0.0-rc.1.25451.107 55 9/9/2025
10.0.0-preview.7.25380.108 38 8/12/2025
10.0.0-preview.6.25358.103 59 7/15/2025
10.0.0-preview.5.25277.114 49 6/7/2025
10.0.0-preview.4.25258.110 61 5/16/2025
10.0.0-preview.3.25171.5 57 4/13/2025
10.0.0-preview.2.25163.2 69 3/21/2025
10.0.0-preview.1.25080.5 85 2/26/2025
9.0.11 33 11/12/2025
9.0.10 38 10/15/2025
9.0.9 47 9/9/2025
9.0.8 55 8/5/2025
9.0.7 62 7/9/2025
9.0.6 74 6/12/2025
9.0.5 58 5/16/2025
9.0.4 74 4/13/2025
9.0.3 75 3/12/2025
9.0.2 78 2/17/2025
9.0.1 101 1/18/2025
9.0.0 94 11/14/2024
9.0.0-rc.2.24473.5 74 10/15/2024
9.0.0-rc.1.24431.7 92 9/12/2024
9.0.0-preview.7.24405.7 75 8/14/2024
9.0.0-preview.6.24327.7 89 7/10/2024
9.0.0-preview.5.24306.7 82 6/14/2024
9.0.0-preview.4.24266.19 81 6/4/2024
9.0.0-preview.3.24172.9 91 4/23/2024
9.0.0-preview.2.24128.5 85 3/16/2024
9.0.0-preview.1.24080.9 80 3/1/2024
8.0.0 115 11/15/2023
8.0.0-rc.2.23479.6 87 10/13/2023
8.0.0-rc.1.23419.4 111 9/22/2023
8.0.0-preview.7.23375.6 123 8/16/2023
8.0.0-preview.6.23329.7 78 7/30/2023
8.0.0-preview.5.23280.8 90 7/31/2023
8.0.0-preview.4.23259.5 100 8/1/2023
8.0.0-preview.3.23174.8 94 5/14/2023
8.0.0-preview.2.23128.3 97 3/29/2023
8.0.0-preview.1.23110.8 93 2/22/2023
7.0.0 95 12/4/2022
7.0.0-rc.2.22472.3 97 10/21/2022
7.0.0-rc.1.22426.10 91 9/15/2022
7.0.0-preview.7.22375.6 115 9/15/2022
7.0.0-preview.6.22324.4 81 9/15/2022
7.0.0-preview.5.22301.12 89 6/27/2022
7.0.0-preview.4.22229.4 97 6/28/2022
7.0.0-preview.3.22175.4 107 6/28/2022
7.0.0-preview.2.22152.2 90 6/28/2022
7.0.0-preview.1.22076.8 79 6/28/2022
6.0.2-mauipre.1.22102.15 101 6/28/2022
6.0.2-mauipre.1.22054.8 96 6/28/2022
6.0.1 79 11/13/2024
6.0.0 123 6/28/2022
6.0.0-rc.2.21480.5 92 6/28/2022
6.0.0-rc.1.21451.13 92 6/28/2022
6.0.0-preview.7.21377.19 95 6/28/2022
6.0.0-preview.6.21352.12 112 6/28/2022
6.0.0-preview.5.21301.5 103 6/28/2022
6.0.0-preview.4.21253.7 96 6/28/2022
6.0.0-preview.3.21201.4 112 6/28/2022
6.0.0-preview.2.21154.6 82 6/28/2022
6.0.0-preview.1.21102.12 87 6/28/2022
5.0.0 93 6/28/2022
5.0.0-rc.2.20475.5 94 6/28/2022
5.0.0-rc.1.20451.14 112 6/28/2022
5.0.0-preview.8.20407.11 97 6/28/2022
5.0.0-preview.7.20364.11 90 6/28/2022
5.0.0-preview.6.20305.6 81 6/28/2022
5.0.0-preview.5.20278.1 107 6/28/2022
5.0.0-preview.4.20251.6 89 6/28/2022
5.0.0-preview.3.20214.6 110 6/28/2022
5.0.0-preview.2.20160.6 85 6/28/2022
5.0.0-preview.1.20120.5 115 6/28/2022
1.7.1 104 6/28/2022
1.7.0 114 6/28/2022
1.7.0-preview3.19551.4 89 6/28/2022
1.7.0-preview2.19523.17 115 6/28/2022
1.7.0-preview1.19504.10 85 6/28/2022
1.6.0 105 6/28/2022
1.6.0-rc1.19456.4 97 6/28/2022
1.6.0-preview9.19421.4 111 6/28/2022
1.6.0-preview9.19416.11 87 6/28/2022
1.6.0-preview8.19405.3 104 6/28/2022
1.6.0-preview7.19362.9 87 6/28/2022
1.6.0-preview6.19303.8 112 6/28/2022
1.6.0-preview6.19264.9 96 6/28/2022
1.6.0-preview5.19224.8 115 6/28/2022
1.6.0-preview4.19212.13 110 6/28/2022
1.6.0-preview3.19128.7 94 6/28/2022
1.6.0-preview.19073.11 86 6/28/2022
1.6.0-preview.18571.3 113 6/28/2022
1.5.0 120 6/28/2022
1.5.0-rc1 86 6/28/2022
1.5.0-preview2-26406-04 97 6/28/2022
1.5.0-preview1-26216-02 86 6/28/2022
1.4.0 123 6/28/2022
1.4.0-preview2-25405-01 102 6/28/2022
1.4.0-preview1-25305-02 85 6/28/2022
1.3.1 125 6/28/2022
1.3.0 106 6/28/2022
1.3.0-preview1-24530-04 95 6/28/2022
1.2.0 101 6/28/2022
1.2.0-rc2-24027 84 6/28/2022
1.1.38-beta-23516 83 6/28/2022
1.1.38-beta-23409 110 6/28/2022
1.1.38-beta-23225 104 6/28/2022
1.1.37 110 6/28/2022
1.1.37-beta-23109 105 6/28/2022
1.1.37-beta-23019 111 6/28/2022
1.1.36 104 6/28/2022
1.1.34-rc 93 6/28/2022
1.1.33-beta 89 6/28/2022
1.1.32-beta 107 6/28/2022