FsToolkit.ErrorHandling 5.0.0-beta002

This is a prerelease version of FsToolkit.ErrorHandling.
There is a newer prerelease version of this package available.
See the version list below for details.
dotnet add package FsToolkit.ErrorHandling --version 5.0.0-beta002
                    
NuGet\Install-Package FsToolkit.ErrorHandling -Version 5.0.0-beta002
                    
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" Version="5.0.0-beta002" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="FsToolkit.ErrorHandling" Version="5.0.0-beta002" />
                    
Directory.Packages.props
<PackageReference Include="FsToolkit.ErrorHandling" />
                    
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 --version 5.0.0-beta002
                    
#r "nuget: FsToolkit.ErrorHandling, 5.0.0-beta002"
                    
#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.
#addin nuget:?package=FsToolkit.ErrorHandling&version=5.0.0-beta002&prerelease
                    
Install FsToolkit.ErrorHandling as a Cake Addin
#tool nuget:?package=FsToolkit.ErrorHandling&version=5.0.0-beta002&prerelease
                    
Install FsToolkit.ErrorHandling 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, .NET Standard2.1 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

Devcontainer

This repository has a devcontainer setup for VSCode. For more infomation see:

Local Setup

Optional

To test fable builds locally you will need:

  • Node
    • v18.0.0 or Higher
    • Not required but recommend that you use NVM to easily manage multiple versions of Node
  • Python
    • v3.10.0 or higher
    • Required for Fable-Python
Compiling
> build.cmd <optional buildtarget> // on windows
$ ./build.sh  <optional buildtarget>// on unix

Without specifying a build target, the default target is DotnetPack, which will run tests for all projects on dotnet and then pack the projects into nuget packages. For additional notable targets see below.

Build Targets
  • Clean - Will clean all projects bin and obj folders
  • DotnetTest - Will run tests for dotnet projects
  • NpmTest - Will run tests for fable-javascript projects
  • PythonTest - Will run tests for fable-python projects
  • RunTests - Will run tests for dotnet, fable-javascript and fable-python projects
  • FormatCode - Will run fantomas to format the codebase

This is not an exhausting list. Additional targets can be found in the ./build/build.fs file.

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 (40)

Showing the top 5 NuGet packages that depend on FsToolkit.ErrorHandling:

Package Downloads
FsToolkit.ErrorHandling.TaskResult

FsToolkit.ErrorHandling is an extensive utility library based around the F# Result type, enabling consistent and powerful error handling.

Oryx

.NET SDK for writing HTTP clients

FsToolkit.ErrorHandling.AsyncSeq

FsToolkit.ErrorHandling is an extensive utility library based around the F# Result type, enabling consistent and powerful error handling.

FsToolkit.ErrorHandling.IcedTasks

FsToolkit.ErrorHandling is an extensive utility library based around the F# Result type, enabling consistent and powerful error handling.

FsToolkit.ErrorHandling.JobResult

FsToolkit.ErrorHandling is an extensive utility library based around the F# Result type, enabling consistent and powerful error handling.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
5.0.0-beta013 59 5/29/2025
5.0.0-beta012 774 5/1/2025
5.0.0-beta011 400 3/30/2025
5.0.0-beta010 222 3/21/2025
5.0.0-beta009 1,651 3/5/2025
5.0.0-beta008 368 3/2/2025
5.0.0-beta007 985 2/23/2025
5.0.0-beta006 164 2/21/2025
5.0.0-beta005 171 2/16/2025
5.0.0-beta004 348 2/4/2025
5.0.0-beta003 373 1/6/2025
5.0.0-beta002 197 12/21/2024
5.0.0-beta001 2,741 12/7/2024
4.18.0 307,194 10/23/2024
4.18.0-beta001 177 10/23/2024
4.17.0 167,825 9/23/2024
4.17.0-beta002 175 9/23/2024
4.17.0-beta001 167 9/23/2024
4.16.0 80,571 7/15/2024
4.15.3 4,981 7/14/2024
4.15.3-beta001 249 7/14/2024
4.15.2 180,046 5/2/2024
4.15.2-beta001 249 5/2/2024
4.15.1 185,987 1/15/2024
4.15.0 58,249 1/10/2024
4.14.0 5,107 1/2/2024
4.13.0 15,187 12/10/2023
4.13.0-beta002 1,273 12/10/2023
4.13.0-beta001 1,232 12/10/2023
4.12.0 12,476 11/27/2023
4.11.1 4,984 11/23/2023
4.11.0 32,093 11/11/2023
4.10.0 22,930 10/16/2023
4.9.0 527,814 7/10/2023
4.8.0 3,343 7/7/2023
4.7.0 18,070 6/21/2023
4.7.0-beta001 1,748 6/21/2023
4.6.0 111,509 4/20/2023
4.6.0-beta001 1,842 4/20/2023
4.5.0 33,642 3/27/2023
4.5.0-beta002 1,821 3/19/2023
4.5.0-beta001 3,274 3/6/2023
4.4.0 188,417 2/21/2023
4.3.0 54,834 1/20/2023
4.2.1 23,100 12/19/2022
4.2.0 2,675 12/17/2022
4.1.0 10,668 12/13/2022
4.1.0-beta001 1,769 12/13/2022
4.0.0 74,083 11/19/2022
4.0.0-beta001 1,739 11/19/2022
3.3.1 70,312 11/19/2022
3.3.1-beta004 1,850 11/19/2022
3.3.1-beta003 1,737 11/18/2022
3.3.1-beta002 1,807 11/18/2022
3.3.1-beta001 1,723 11/18/2022
3.3.0-beta001 1,758 11/9/2022
3.2.0 133,455 10/31/2022
3.2.0-beta001 1,631 10/31/2022
3.1.0 27,055 10/19/2022
3.0.1 3,672 10/18/2022
3.0.0 8,779 10/14/2022
3.0.0-beta008 1,812 10/14/2022
3.0.0-beta007 33,867 4/15/2022
3.0.0-beta006 1,867 4/5/2022
3.0.0-beta005 1,905 4/5/2022
3.0.0-beta004 1,908 4/5/2022
3.0.0-beta003 1,836 3/30/2022
3.0.0-beta002 2,524 2/21/2022
3.0.0-beta001 1,824 2/21/2022
2.13.0 1,521,400 1/11/2022
2.13.0-beta001 1,795 1/11/2022
2.12.0 4,172 1/6/2022
2.12.0-beta001 1,786 1/6/2022
2.11.1 39,485 12/1/2021
2.11.1-beta001 2,391 12/1/2021
2.11.0 9,505 11/24/2021
2.11.0-beta004 4,858 11/24/2021
2.11.0-beta002 4,763 11/24/2021
2.11.0-beta001 4,700 11/24/2021
2.10.0 37,508 11/13/2021
2.9.0 8,078 11/10/2021
2.9.0-beta001 1,889 11/10/2021
2.8.1 8,458 11/7/2021
2.8.0 2,389 11/7/2021
2.8.0-beta001 2,070 11/7/2021
2.7.1 10,754 10/19/2021
2.7.1-beta001 1,929 10/19/2021
2.7.0 198,172 8/2/2021
2.7.0-beta001 2,037 8/2/2021
2.6.0 49,409 7/7/2021
2.6.0-beta001 2,031 7/7/2021
2.5.0 63,279 5/26/2021
2.5.0-beta001 2,098 5/26/2021
2.4.0 10,189 5/23/2021
2.4.0-beta001 1,979 5/23/2021
2.3.0 21,323 5/14/2021
2.3.0-beta002 1,908 5/14/2021
2.2.0 15,333 4/21/2021
2.1.2 87,980 2/27/2021
2.1.1 3,208 2/26/2021
2.1.1-beta001 2,051 2/26/2021
2.1.0 2,573 2/26/2021
2.1.0-beta003 2,126 2/26/2021
2.1.0-beta002 1,928 2/25/2021
2.1.0-beta001 2,075 2/25/2021
2.0.0 656,826 11/20/2020
2.0.0-beta002 2,304 11/18/2020
2.0.0-beta001 2,710 8/29/2020
1.4.3 263,417 7/22/2020
1.4.0 10,241 6/5/2020
1.3.2 2,796 6/5/2020
1.3.1 4,843 5/29/2020
1.3.1-beta001 2,319 5/25/2020
1.3.0 6,323 5/25/2020
1.3.0-beta006 2,254 5/25/2020
1.3.0-beta005 2,361 5/25/2020
1.3.0-beta004 2,346 5/12/2020
1.2.6 38,854 2/15/2020
1.2.5 30,943 10/18/2019
1.2.4 3,270 10/10/2019
1.2.3 119,917 7/22/2019
1.2.2 7,016 5/31/2019
1.2.1 28,521 5/22/2019
1.1.1 3,166 5/9/2019
1.1.0 2,941 5/7/2019
1.0.0 5,387 4/10/2019
0.0.14 2,883 1/27/2019
0.0.13 1,524 1/21/2019
0.0.12 1,871 1/4/2019
0.0.11 1,605 1/3/2019
0.0.10 1,581 12/30/2018
0.0.9 1,781 10/5/2018
0.0.8 1,680 10/5/2018
0.0.7 1,697 10/5/2018
0.0.6 1,633 10/4/2018
0.0.5 1,612 9/16/2018
0.0.4 1,635 9/16/2018
0.0.3 1,667 9/8/2018
0.0.2 1,664 9/8/2018
0.0.1 2,066 9/8/2018

- BREAKING: [Remove Ply and update to FSharp 6](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/248) Credits @TheAngryByrd
- BREAKING: [Remove MergeSources (and!) from some implementations like Result](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/261)  Credits @TheAngryByrd
- BREAKING: [Merge TaskResult into Core library](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/285) Credits @TheAngryByrd
- This means FsToolkit.ErrorHandling.TaskResult is no longer a separate package and will not be updated. It is now part of the core library.
- BREAKING: [Rename retn to singleton](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/287) Credits @1eyewonder
- [Use Microsoft.Bcl.AsyncInterfaces in netstandard2.0 (Allows IAsyncDisposable and IAsyncEnumerable)](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/250) Credits @TheAngryByrd
- [Build against Net8](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/251) Credits @TheAngryByrd
- [Fix Overload Resolution to Align to Computation Expression used](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/252) Credits @TheAngryByrd
- [refactor!: Seq.sequenceResultM returns Array instead of seq](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/255) Credits @bartelink
- [feat(Seq): sequenceResultA](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/255) Credits @bartelink
- [Updated uses of Seq.append](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/290) Credits @1eyewonder
-