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
213
Microsoft.VisualStudio.Debugger.Contracts
Package containing extensibility contracts between the debugger and other Visual Studio components, such as language services.
200
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
196
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
181
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
179
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
176
Microsoft.Build.Tasks.Core
This package contains the Microsoft.Build.Tasks assembly which implements the commonly used tasks of MSBuild.
174
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
170
Microsoft.VisualStudio.Web.CodeGeneration.Contracts
Contains interfaces for Project Model and messaging for scaffolding.
167
Microsoft.Build
This package contains the Microsoft.Build assembly which is used to create, edit, and evaluate MSBuild projects.
167
Microsoft.Build.Tasks.Core
This package contains the Microsoft.Build.Tasks assembly which implements the commonly used tasks of MSBuild.
167
Microsoft.Build.Utilities.Core
This package contains the Microsoft.Build.Utilities assembly which is used to implement custom MSBuild tasks.
167
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
166
Microsoft.Build.Utilities.Core
This package contains the Microsoft.Build.Utilities assembly which is used to implement custom MSBuild tasks.
165
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.
165
Microsoft.Build.Tasks.Core
This package contains the Microsoft.Build.Tasks assembly which implements the commonly used tasks of MSBuild.
164
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
163
MessagePack
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
163
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
161

.NET Framework 4.6.2

.NET 8.0

  • No dependencies.

.NET 9.0

  • No dependencies.

.NET Standard 2.0

Version Downloads Last updated
11.0.0-preview.4.26230.115 8 5/13/2026
11.0.0-preview.3.26207.106 10 5/3/2026
11.0.0-preview.2.26159.112 13 3/12/2026
11.0.0-preview.1.26104.118 14 2/12/2026
10.0.8 8 5/13/2026
10.0.7 11 5/3/2026
10.0.6 10 5/3/2026
10.0.5 14 3/12/2026
10.0.4 12 3/12/2026
10.0.3 15 2/12/2026
10.0.2 20 1/15/2026
10.0.1 34 12/10/2025
10.0.0 53 11/12/2025
10.0.0-rc.2.25502.107 58 10/15/2025
10.0.0-rc.1.25451.107 75 9/9/2025
10.0.0-preview.7.25380.108 61 8/12/2025
10.0.0-preview.6.25358.103 83 7/15/2025
10.0.0-preview.5.25277.114 70 6/7/2025
10.0.0-preview.4.25258.110 90 5/16/2025
10.0.0-preview.3.25171.5 78 4/13/2025
10.0.0-preview.2.25163.2 90 3/21/2025
10.0.0-preview.1.25080.5 103 2/26/2025
9.0.16 9 5/13/2026
9.0.15 9 5/3/2026
9.0.14 15 3/12/2026
9.0.13 17 2/12/2026
9.0.12 21 1/15/2026
9.0.11 53 11/12/2025
9.0.10 66 10/15/2025
9.0.9 72 9/9/2025
9.0.8 83 8/5/2025
9.0.7 87 7/9/2025
9.0.6 94 6/12/2025
9.0.5 79 5/16/2025
9.0.4 94 4/13/2025
9.0.3 98 3/12/2025
9.0.2 96 2/17/2025
9.0.1 124 1/18/2025
9.0.0 113 11/14/2024
9.0.0-rc.2.24473.5 98 10/15/2024
9.0.0-rc.1.24431.7 115 9/12/2024
9.0.0-preview.7.24405.7 94 8/14/2024
9.0.0-preview.6.24327.7 113 7/10/2024
9.0.0-preview.5.24306.7 102 6/14/2024
9.0.0-preview.4.24266.19 106 6/4/2024
9.0.0-preview.3.24172.9 116 4/23/2024
9.0.0-preview.2.24128.5 108 3/16/2024
9.0.0-preview.1.24080.9 102 3/1/2024
8.0.0 139 11/15/2023
8.0.0-rc.2.23479.6 104 10/13/2023
8.0.0-rc.1.23419.4 156 9/22/2023
8.0.0-preview.7.23375.6 149 8/16/2023
8.0.0-preview.6.23329.7 103 7/30/2023
8.0.0-preview.5.23280.8 116 7/31/2023
8.0.0-preview.4.23259.5 119 8/1/2023
8.0.0-preview.3.23174.8 112 5/14/2023
8.0.0-preview.2.23128.3 115 3/29/2023
8.0.0-preview.1.23110.8 115 2/22/2023
7.0.0 120 12/4/2022
7.0.0-rc.2.22472.3 116 10/21/2022
7.0.0-rc.1.22426.10 110 9/15/2022
7.0.0-preview.7.22375.6 136 9/15/2022
7.0.0-preview.6.22324.4 105 9/15/2022
7.0.0-preview.5.22301.12 112 6/27/2022
7.0.0-preview.4.22229.4 117 6/28/2022
7.0.0-preview.3.22175.4 128 6/28/2022
7.0.0-preview.2.22152.2 108 6/28/2022
7.0.0-preview.1.22076.8 96 6/28/2022
6.0.2-mauipre.1.22102.15 123 6/28/2022
6.0.2-mauipre.1.22054.8 121 6/28/2022
6.0.1 99 11/13/2024
6.0.0 144 6/28/2022
6.0.0-rc.2.21480.5 111 6/28/2022
6.0.0-rc.1.21451.13 115 6/28/2022
6.0.0-preview.7.21377.19 111 6/28/2022
6.0.0-preview.6.21352.12 133 6/28/2022
6.0.0-preview.5.21301.5 129 6/28/2022
6.0.0-preview.4.21253.7 120 6/28/2022
6.0.0-preview.3.21201.4 141 6/28/2022
6.0.0-preview.2.21154.6 100 6/28/2022
6.0.0-preview.1.21102.12 120 6/28/2022
5.0.0 122 6/28/2022
5.0.0-rc.2.20475.5 116 6/28/2022
5.0.0-rc.1.20451.14 131 6/28/2022
5.0.0-preview.8.20407.11 124 6/28/2022
5.0.0-preview.7.20364.11 108 6/28/2022
5.0.0-preview.6.20305.6 101 6/28/2022
5.0.0-preview.5.20278.1 129 6/28/2022
5.0.0-preview.4.20251.6 109 6/28/2022
5.0.0-preview.3.20214.6 133 6/28/2022
5.0.0-preview.2.20160.6 109 6/28/2022
5.0.0-preview.1.20120.5 141 6/28/2022
1.7.1 120 6/28/2022
1.7.0 136 6/28/2022
1.7.0-preview3.19551.4 123 6/28/2022
1.7.0-preview2.19523.17 131 6/28/2022
1.7.0-preview1.19504.10 107 6/28/2022
1.6.0 123 6/28/2022
1.6.0-rc1.19456.4 115 6/28/2022
1.6.0-preview9.19421.4 132 6/28/2022
1.6.0-preview9.19416.11 111 6/28/2022
1.6.0-preview8.19405.3 121 6/28/2022
1.6.0-preview7.19362.9 108 6/28/2022
1.6.0-preview6.19303.8 130 6/28/2022
1.6.0-preview6.19264.9 115 6/28/2022
1.6.0-preview5.19224.8 156 6/28/2022
1.6.0-preview4.19212.13 135 6/28/2022
1.6.0-preview3.19128.7 116 6/28/2022
1.6.0-preview.19073.11 105 6/28/2022
1.6.0-preview.18571.3 136 6/28/2022
1.5.0 151 6/28/2022
1.5.0-rc1 107 6/28/2022
1.5.0-preview2-26406-04 123 6/28/2022
1.5.0-preview1-26216-02 108 6/28/2022
1.4.0 143 6/28/2022
1.4.0-preview2-25405-01 124 6/28/2022
1.4.0-preview1-25305-02 104 6/28/2022
1.3.1 148 6/28/2022
1.3.0 125 6/28/2022
1.3.0-preview1-24530-04 112 6/28/2022
1.2.0 122 6/28/2022
1.2.0-rc2-24027 108 6/28/2022
1.1.38-beta-23516 102 6/28/2022
1.1.38-beta-23409 128 6/28/2022
1.1.38-beta-23225 128 6/28/2022
1.1.37 133 6/28/2022
1.1.37-beta-23109 132 6/28/2022
1.1.37-beta-23019 128 6/28/2022
1.1.36 128 6/28/2022
1.1.34-rc 117 6/28/2022
1.1.33-beta 112 6/28/2022
1.1.32-beta 126 6/28/2022