FsToolkit.ErrorHandling.AsyncSeq 4.0.0-beta001

This is a prerelease version of FsToolkit.ErrorHandling.AsyncSeq.
There is a newer version of this package available.
See the version list below for details.
dotnet add package FsToolkit.ErrorHandling.AsyncSeq --version 4.0.0-beta001
                    
NuGet\Install-Package FsToolkit.ErrorHandling.AsyncSeq -Version 4.0.0-beta001
                    
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="FsToolkit.ErrorHandling.AsyncSeq" Version="4.0.0-beta001" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="FsToolkit.ErrorHandling.AsyncSeq" Version="4.0.0-beta001" />
                    
Directory.Packages.props
<PackageReference Include="FsToolkit.ErrorHandling.AsyncSeq" />
                    
Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.
paket add FsToolkit.ErrorHandling.AsyncSeq --version 4.0.0-beta001
                    
#r "nuget: FsToolkit.ErrorHandling.AsyncSeq, 4.0.0-beta001"
                    
#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.
#:package FsToolkit.ErrorHandling.AsyncSeq@4.0.0-beta001
                    
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.
#addin nuget:?package=FsToolkit.ErrorHandling.AsyncSeq&version=4.0.0-beta001&prerelease
                    
Install as a Cake Addin
#tool nuget:?package=FsToolkit.ErrorHandling.AsyncSeq&version=4.0.0-beta001&prerelease
                    
Install as a Cake Tool

FsToolkit.ErrorHandling

FsToolkit.ErrorHandling is a utility library to work with the Result type in F#, and allows you to do clear, simple and powerful error handling.

The library provides utility functions like map, bind, apply, traverse, sequence as well as computation expressions and infix operators to work with Result<'a, 'b>, Result<'a option, 'b>, Async<Result<'a, 'b>>, Async<Result<'a option, 'b>>, and Result<'a, 'b list>.

It was inspired by Chessie and Cvdm.ErrorHandling (the latter has now been merged into FsToolkit.ErrorHandling).

FsToolkit.ErrorHandling targets .NET Standard 2.0 and .NET Framework 4.6.1 and supports Fable.

Documentation

The documentation is available here.

Further material

Builds

GitHub Actions
GitHub Actions
Build History

NuGet

Package name Release Prelease
FsToolkit.ErrorHandling NuGet NuGet
FsToolkit.ErrorHandling.TaskResult NuGet NuGet
FsToolkit.ErrorHandling.JobResult NuGet NuGet
FsToolkit.ErrorHandling.AsyncSeq NuGet NuGet
FsToolkit.ErrorHandling.IcedTasks NuGet NuGet

Developing locally

Requirements
Compiling
> build.cmd <optional buildtarget> // on windows
$ ./build.sh  <optional buildtarget>// on unix

A motivating example

This example of composing a login flow shows one example of how this library can aid in clear, simple, and powerful error handling, using just a computation expression and a few helper functions. (The library has many more helper functions and computation expressions as well as infix operators; see the documentation for details.)

// Given the following functions:
//   tryGetUser: string -> Async<User option>
//   isPwdValid: string -> User -> bool
//   authorize: User -> Async<Result<unit, AuthError>>
//   createAuthToken: User -> Result<AuthToken, TokenError>

type LoginError = InvalidUser | InvalidPwd | Unauthorized of AuthError | TokenErr of TokenError

let login (username: string) (password: string) : Async<Result<AuthToken, LoginError>> =
  asyncResult {
    // requireSome unwraps a Some value or gives the specified error if None
    let! user = username |> tryGetUser |> AsyncResult.requireSome InvalidUser

    // requireTrue gives the specified error if false
    do! user |> isPwdValid password |> Result.requireTrue InvalidPwd

    // Error value is wrapped/transformed (Unauthorized has signature AuthError -> LoginError)
    do! user |> authorize |> AsyncResult.mapError Unauthorized

    // Same as above, but synchronous, so we use the built-in mapError
    return! user |> createAuthToken |> Result.mapError TokenErr
  }

Sponsor(s)

<a href="https://www.ajira.tech"><img src="./Ajira-logo.png" alt="Ajira Technologies, India" width="200" /></a>

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  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 was computed.  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.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework 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 tizen40 was computed.  tizen60 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.

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
5.1.0 100 9/26/2025
5.1.0-beta001 96 9/26/2025
5.0.1 387 7/12/2025
5.0.0 227 6/2/2025
5.0.0-beta014 159 6/2/2025
5.0.0-beta013 181 5/29/2025
5.0.0-beta012 682 5/1/2025
5.0.0-beta011 213 3/30/2025
5.0.0-beta010 147 3/21/2025
5.0.0-beta009 747 3/5/2025
5.0.0-beta008 143 3/2/2025
5.0.0-beta007 202 2/23/2025
5.0.0-beta006 143 2/21/2025
5.0.0-beta005 153 2/16/2025
5.0.0-beta004 160 2/4/2025
5.0.0-beta003 144 1/6/2025
5.0.0-beta002 137 12/21/2024
5.0.0-beta001 140 12/7/2024
4.18.0 40,792 10/23/2024
4.18.0-beta001 141 10/23/2024
4.17.0 280 9/23/2024
4.17.0-beta002 110 9/23/2024
4.17.0-beta001 133 9/23/2024
4.16.0 505 7/15/2024
4.15.3 214 7/14/2024
4.15.3-beta001 145 7/14/2024
4.15.2 285 5/2/2024
4.15.2-beta001 135 5/2/2024
4.15.1 617 1/15/2024
4.15.0 42,074 1/10/2024
4.14.0 492 1/2/2024
4.13.0 280 12/10/2023
4.13.0-beta002 165 12/10/2023
4.13.0-beta001 147 12/10/2023
4.12.0 220 11/27/2023
4.11.1 211 11/23/2023
4.11.0 206 11/11/2023
4.10.0 239 10/16/2023
4.9.0 2,118 7/10/2023
4.8.0 258 7/7/2023
4.7.0 277 6/21/2023
4.7.0-beta001 218 6/21/2023
4.6.0 2,785 4/20/2023
4.6.0-beta001 201 4/20/2023
4.5.0 1,207 3/27/2023
4.5.0-beta002 209 3/19/2023
4.5.0-beta001 226 3/6/2023
4.4.0 354 2/21/2023
4.3.0 425 1/20/2023
4.2.1 412 12/19/2022
4.2.0 418 12/17/2022
4.1.0 379 12/13/2022
4.1.0-beta001 218 12/13/2022
4.0.0 496 11/19/2022
4.0.0-beta001 253 11/19/2022
3.3.1 41,395 11/19/2022
3.3.1-beta004 234 11/19/2022
3.3.1-beta003 248 11/18/2022
3.3.1-beta002 213 11/18/2022
3.3.1-beta001 238 11/18/2022
3.3.0-beta001 230 11/9/2022
3.2.0 4,630 10/31/2022
3.2.0-beta001 213 10/31/2022
3.1.0 619 10/19/2022
3.0.1 494 10/18/2022
3.0.0 568 10/14/2022
3.0.0-beta008 248 10/14/2022
3.0.0-beta007 9,272 4/15/2022
3.0.0-beta006 285 4/5/2022
3.0.0-beta005 297 4/5/2022
3.0.0-beta004 247 4/5/2022
3.0.0-beta003 273 3/30/2022
3.0.0-beta002 277 2/21/2022
3.0.0-beta001 294 2/21/2022
2.13.0 6,790 1/11/2022
2.13.0-beta001 317 1/11/2022
2.12.0 402 1/6/2022
2.12.0-beta001 299 1/6/2022
2.11.1 1,529 12/1/2021
2.11.1-beta001 891 12/1/2021
2.11.0 3,366 11/24/2021
2.11.0-beta004 3,289 11/24/2021
2.11.0-beta002 3,317 11/24/2021
2.11.0-beta001 3,208 11/24/2021

- BREAKING: [Better alignment with FSharp.Core Result functions](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/199). Credits @TheAngryByrd
- [Adding Option.either and friends](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/198). Credits @TheAngryByrd
- [Fixes for Option.tryParse and tryGetValue](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/197). Credits @TheAngryByrd