FsToolkit.ErrorHandling.AsyncSeq 2.13.0-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There is a newer version of this package available.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 2.13.0-beta001
                    
NuGet\Install-Package FsToolkit.ErrorHandling.AsyncSeq -Version 2.13.0-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="2.13.0-beta001" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="FsToolkit.ErrorHandling.AsyncSeq" Version="2.13.0-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 2.13.0-beta001
                    
#r "nuget: FsToolkit.ErrorHandling.AsyncSeq, 2.13.0-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@2.13.0-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=2.13.0-beta001&prerelease
                    
Install as a Cake Addin
#tool nuget:?package=FsToolkit.ErrorHandling.AsyncSeq&version=2.13.0-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 Badge
FsToolkit.ErrorHandling NuGet
FsToolkit.ErrorHandling.TaskResult NuGet
FsToolkit.ErrorHandling.JobResult NuGet
FsToolkit.ErrorHandling.AsyncSeq NuGet

Developing locally

Requirements
  • .NET Core SDK
    • v3.1.200 or higher
    • Install from here.
  • Node
    • v10.15.0 or LTS
    • Not required but recommend that you use NVM to easily manage multiple versions of Node
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 was computed. 
.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
5.0.1 123 7/12/2025
5.0.0 172 6/2/2025
5.0.0-beta014 134 6/2/2025
5.0.0-beta013 146 5/29/2025
5.0.0-beta012 565 5/1/2025
5.0.0-beta011 186 3/30/2025
5.0.0-beta010 122 3/21/2025
5.0.0-beta009 724 3/5/2025
5.0.0-beta008 120 3/2/2025
5.0.0-beta007 168 2/23/2025
5.0.0-beta006 114 2/21/2025
5.0.0-beta005 114 2/16/2025
5.0.0-beta004 127 2/4/2025
5.0.0-beta003 115 1/6/2025
5.0.0-beta002 116 12/21/2024
5.0.0-beta001 116 12/7/2024
4.18.0 31,849 10/23/2024
4.18.0-beta001 100 10/23/2024
4.17.0 227 9/23/2024
4.17.0-beta002 88 9/23/2024
4.17.0-beta001 103 9/23/2024
4.16.0 434 7/15/2024
4.15.3 165 7/14/2024
4.15.3-beta001 109 7/14/2024
4.15.2 232 5/2/2024
4.15.2-beta001 101 5/2/2024
4.15.1 570 1/15/2024
4.15.0 42,028 1/10/2024
4.14.0 454 1/2/2024
4.13.0 229 12/10/2023
4.13.0-beta002 133 12/10/2023
4.13.0-beta001 114 12/10/2023
4.12.0 186 11/27/2023
4.11.1 178 11/23/2023
4.11.0 170 11/11/2023
4.10.0 215 10/16/2023
4.9.0 2,088 7/10/2023
4.8.0 227 7/7/2023
4.7.0 234 6/21/2023
4.7.0-beta001 177 6/21/2023
4.6.0 2,752 4/20/2023
4.6.0-beta001 160 4/20/2023
4.5.0 1,164 3/27/2023
4.5.0-beta002 163 3/19/2023
4.5.0-beta001 184 3/6/2023
4.4.0 308 2/21/2023
4.3.0 386 1/20/2023
4.2.1 367 12/19/2022
4.2.0 370 12/17/2022
4.1.0 333 12/13/2022
4.1.0-beta001 176 12/13/2022
4.0.0 442 11/19/2022
4.0.0-beta001 200 11/19/2022
3.3.1 41,346 11/19/2022
3.3.1-beta004 186 11/19/2022
3.3.1-beta003 197 11/18/2022
3.3.1-beta002 163 11/18/2022
3.3.1-beta001 192 11/18/2022
3.3.0-beta001 193 11/9/2022
3.2.0 4,588 10/31/2022
3.2.0-beta001 173 10/31/2022
3.1.0 575 10/19/2022
3.0.1 443 10/18/2022
3.0.0 515 10/14/2022
3.0.0-beta008 210 10/14/2022
3.0.0-beta007 9,218 4/15/2022
3.0.0-beta006 226 4/5/2022
3.0.0-beta005 241 4/5/2022
3.0.0-beta004 209 4/5/2022
3.0.0-beta003 219 3/30/2022
3.0.0-beta002 222 2/21/2022
3.0.0-beta001 241 2/21/2022
2.13.0 6,734 1/11/2022
2.13.0-beta001 263 1/11/2022
2.12.0 353 1/6/2022
2.12.0-beta001 244 1/6/2022
2.11.1 1,489 12/1/2021
2.11.1-beta001 843 12/1/2021
2.11.0 3,313 11/24/2021
2.11.0-beta004 3,248 11/24/2021
2.11.0-beta002 3,263 11/24/2021
2.11.0-beta001 3,170 11/24/2021

- [Option/ValueOption.ofNull and bindNull](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/164) Credits [@TheAngryByrd](https://github.com/TheAngryByrd)