Optional2 5.1.0

Requires NuGet 2.12 or higher.

dotnet add package Optional2 --version 5.1.0
NuGet\Install-Package Optional2 -Version 5.1.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Optional2" Version="5.1.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Optional2 --version 5.1.0
#r "nuget: Optional2, 5.1.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Optional2 as a Cake Addin
#addin nuget:?package=Optional2&version=5.1.0

// Install Optional2 as a Cake Tool
#tool nuget:?package=Optional2&version=5.1.0



Optional is a robust option/maybe type for C#. Originally developed by Nils Lück - Optional

alternate text is missing from this package README image

What and Why?

Optional is a strongly typed alternative to null values that lets you:

  • Avoid those pesky null-reference exceptions
  • Signal intent and model your data more explictly
  • Cut down on manual null checks and focus on your domain
  • Work with optional values of reference and value types in the same way. Two versions of the same generic method with where T : class and where T : struct are no longer needed


PM> Install-Package Optional2

NuGet package. Supports .NET 3.5+ and .NET (.NET Standard 1.0+)


Using the library

To use Optional simply import the following namespace:

using Optional;

A few auxiliary namespaces are provided:

using Optional.Linq; // Linq query syntax support
using Optional.Unsafe; // Unsafe value retrieval
using Optional.Collections; // Linq like methods with Option specifics

Creating optional values

// The most basic way to create optional values is to use the static `Option` class:
var none = Option.None<int>();
var some = Option.Some(10);
// or use extension methods:
var none = 10.None(); // Equivalent to Option.None<int>()
var some = 10.Some();

Option can be filtered during creation by methods .Some*() or .None*(). The most useful from them is .SomeNotNull() since Nullable Reference Types are supported. Analogue for value types is .ToOption().

Retrieving values

When retrieving values, Optional forces you to consider both cases (that is if a value is present or not).

Like Nullable<T> Option can be tested by HasValue property. There are also more precise ways:

var isThousand = option.Contains(1000);
var isGreaterThanThousand = option.Exists(val => val > 1000);

Ways to retrieve a value from Option are:

var value = option.ValueOr(10); // Returns the value if Some, or otherwise an alternative value (10)
var value = option.Match(
  some: x => x + 1, 
  none: () => 10
); // pattern matching
var value = option.ValueOrFailure(); // Unsafe: throws OptionValueMissingException on None

Transforming and filtering values

var value = 10.Some();
var doubled = value.Map(x => x * 2); // Some(20)
var odd = doubled.Filter(x => x % 2 == 1); // None
var fallback = odd.Else(1.Some()); // Some(1)

For details see Option<T> or explore xml doc.

Other utilities

Monadic evaluation with LINQ query syntax

using Optional.Linq;

var personWithGreenHair =
  from person in FindPersonById(10)
  from hairstyle in GetHairstyle(person)
  where hairstyle.Color == "green"
  select person;

Options with exceptional values aka Either

An Option<T, TException> type with similar capabilities.

var none = Option.None<int, ErrorCode>(ErrorCode.GeneralError);
var some = Option.Some<int, ErrorCode>(10);

Working with collections

  • IEnumerable<T> related Linq similar methods (First|Last|Signle)OrNone()
  • items.Values() keeps only Some from items and unwraps them
  • dictionary.GetValueOrNone(key: 42) - lookups an entry by key
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp1.0 was computed.  netcoreapp1.1 was computed.  netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard1.0 is compatible.  netstandard1.1 was computed.  netstandard1.2 was computed.  netstandard1.3 was computed.  netstandard1.4 was computed.  netstandard1.5 was computed.  netstandard1.6 was computed.  netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework net35 is compatible.  net40 is compatible.  net403 was computed.  net45 is compatible.  net451 was computed.  net452 was computed.  net46 was computed.  net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen30 was computed.  tizen40 was computed.  tizen60 was computed. 
Universal Windows Platform uap was computed.  uap10.0 was computed. 
Windows Phone wp8 was computed.  wp81 was computed.  wpa81 was computed. 
Windows Store netcore was computed.  netcore45 was computed.  netcore451 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.
  • .NETFramework 3.5

    • No dependencies.
  • .NETFramework 4.0

    • No dependencies.
  • .NETFramework 4.5

    • No dependencies.
  • .NETStandard 1.0

  • .NETStandard 2.0

    • No dependencies.
  • .NETStandard 2.1

    • No dependencies.
  • net6.0

    • No dependencies.
  • net7.0

    • No dependencies.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
5.1.0 232 11/10/2023
5.0.0 116 10/7/2023
4.5.0 80 11/10/2023
4.4.0 110 10/7/2023
4.3.0 109 10/6/2023
4.2.1-alpha 95 9/10/2023
4.2.0 699 9/10/2023
4.1.0 521 9/1/2023
4.1.0-rc2 116 9/1/2023
4.1.0-rc1 119 8/31/2023