Optional.Async 1.3.0

.NET Standard 2.0
dotnet add package Optional.Async --version 1.3.0
NuGet\Install-Package Optional.Async -Version 1.3.0
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="Optional.Async" Version="1.3.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Optional.Async --version 1.3.0
#r "nuget: Optional.Async, 1.3.0"
#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 Optional.Async as a Cake Addin
#addin nuget:?package=Optional.Async&version=1.3.0

// Install Optional.Async as a Cake Tool
#tool nuget:?package=Optional.Async&version=1.3.0


Async extensions for Nils Luck's Optional library.

It allows you to chain Task<Option<T>> and Task<Option<T, TException>> without having to use await.

Since version 5.0, the Optional library will include its own async extensions. However, at this point they don't provide as much flexibility. To avoid conflicts, the namespace of this library has been changed to Optional.Async.Extensions.

Note: Optional.Async was not meant to be published as a standalone library. It's a collection of extension methods that I had to implement on my own while working with Optional. There are currently no tests and I don't plan on extensively maintaining it. Still, most of the extensions you'll find here are currently being used/have been used for the past year in production code without issues.


Say you have the following asynchronous functions and you want to execute them in order:

Task<Option<User, Error>> CheckIfUserIsAuthorized(string userId, string category);

Task<Option<CloudRecord, Error>> StoreTheFileIntoTheCloud(File file, string category);

Task<Option<Guid, Error>> StoreDatabaseLog(CloudRecord record);

Task<Option<DocumentProcessedResult, Error>> SendToExternalService(Guid key);

Currently, there is no built-in mechanism inside Optional that allows you to chain these calls. What Optional.Async provides is the ability to compose asynchronous functions. The following would be valid syntax:

Task<Option<DocumentProcessedResult, Error>> ProcessDocument(
    string userId,
    string category,
    File file) =>
    CheckIfUserIsAuthorized(userId, category).FlatMapAsync(user =>
    StoreTheFileIntoTheCloud(file, category).FlatMapAsync(cloudRecord =>
    StoreDatabaseLog(cloudRecord).FlatMapAsync(uniqueKey =>

See the DevAdventures RealWorld project and the DDD Café for more examples.

Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows net7.0 net7.0-android net7.0-ios net7.0-maccatalyst net7.0-macos net7.0-tvos net7.0-windows
.NET Core netcoreapp2.0 netcoreapp2.1 netcoreapp2.2 netcoreapp3.0 netcoreapp3.1
.NET Standard netstandard2.0 netstandard2.1
.NET Framework net461 net462 net463 net47 net471 net472 net48 net481
MonoAndroid monoandroid
MonoMac monomac
MonoTouch monotouch
Tizen tizen40 tizen60
Xamarin.iOS xamarinios
Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (2)

Showing the top 2 NuGet packages that depend on Optional.Async:

Package Downloads

Refit based web api client management, but resilient (retry, connectivity, cache, auth, log, priority...)


Provides base commands, queries and handlers.

GitHub repositories (1)

Showing the top 1 popular GitHub repositories that depend on Optional.Async:

Repository Stars
A RealWorld application implemented using the Dev Adventures .NET Core template and functional programming.
Version Downloads Last updated
1.3.0 225,961 6/19/2019
1.2.0 3,675 2/8/2019
1.1.0 3,914 11/26/2018
1.0.0 1,618 11/23/2018