FsToolkit.ErrorHandling.AsyncSeq 3.0.0-beta002

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There is a newer version of this package available.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 3.0.0-beta002
                    
NuGet\Install-Package FsToolkit.ErrorHandling.AsyncSeq -Version 3.0.0-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.AsyncSeq" Version="3.0.0-beta002" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="FsToolkit.ErrorHandling.AsyncSeq" Version="3.0.0-beta002" />
                    
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 3.0.0-beta002
                    
#r "nuget: FsToolkit.ErrorHandling.AsyncSeq, 3.0.0-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.
#:package FsToolkit.ErrorHandling.AsyncSeq@3.0.0-beta002
                    
#: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=3.0.0-beta002&prerelease
                    
Install as a Cake Addin
#tool nuget:?package=FsToolkit.ErrorHandling.AsyncSeq&version=3.0.0-beta002&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 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
5.0.1 115 7/12/2025
5.0.0 171 6/2/2025
5.0.0-beta014 133 6/2/2025
5.0.0-beta013 145 5/29/2025
5.0.0-beta012 539 5/1/2025
5.0.0-beta011 185 3/30/2025
5.0.0-beta010 121 3/21/2025
5.0.0-beta009 723 3/5/2025
5.0.0-beta008 119 3/2/2025
5.0.0-beta007 167 2/23/2025
5.0.0-beta006 113 2/21/2025
5.0.0-beta005 113 2/16/2025
5.0.0-beta004 126 2/4/2025
5.0.0-beta003 114 1/6/2025
5.0.0-beta002 115 12/21/2024
5.0.0-beta001 115 12/7/2024
4.18.0 31,227 10/23/2024
4.18.0-beta001 99 10/23/2024
4.17.0 226 9/23/2024
4.17.0-beta002 87 9/23/2024
4.17.0-beta001 102 9/23/2024
4.16.0 433 7/15/2024
4.15.3 163 7/14/2024
4.15.3-beta001 108 7/14/2024
4.15.2 231 5/2/2024
4.15.2-beta001 100 5/2/2024
4.15.1 569 1/15/2024
4.15.0 42,027 1/10/2024
4.14.0 453 1/2/2024
4.13.0 228 12/10/2023
4.13.0-beta002 132 12/10/2023
4.13.0-beta001 113 12/10/2023
4.12.0 185 11/27/2023
4.11.1 177 11/23/2023
4.11.0 169 11/11/2023
4.10.0 214 10/16/2023
4.9.0 2,085 7/10/2023
4.8.0 224 7/7/2023
4.7.0 231 6/21/2023
4.7.0-beta001 174 6/21/2023
4.6.0 2,749 4/20/2023
4.6.0-beta001 157 4/20/2023
4.5.0 1,161 3/27/2023
4.5.0-beta002 160 3/19/2023
4.5.0-beta001 181 3/6/2023
4.4.0 305 2/21/2023
4.3.0 383 1/20/2023
4.2.1 364 12/19/2022
4.2.0 367 12/17/2022
4.1.0 330 12/13/2022
4.1.0-beta001 173 12/13/2022
4.0.0 439 11/19/2022
4.0.0-beta001 197 11/19/2022
3.3.1 41,343 11/19/2022
3.3.1-beta004 183 11/19/2022
3.3.1-beta003 194 11/18/2022
3.3.1-beta002 160 11/18/2022
3.3.1-beta001 189 11/18/2022
3.3.0-beta001 190 11/9/2022
3.2.0 4,585 10/31/2022
3.2.0-beta001 170 10/31/2022
3.1.0 572 10/19/2022
3.0.1 440 10/18/2022
3.0.0 512 10/14/2022
3.0.0-beta008 207 10/14/2022
3.0.0-beta007 9,217 4/15/2022
3.0.0-beta006 225 4/5/2022
3.0.0-beta005 240 4/5/2022
3.0.0-beta004 208 4/5/2022
3.0.0-beta003 218 3/30/2022
3.0.0-beta002 221 2/21/2022
3.0.0-beta001 240 2/21/2022
2.13.0 6,733 1/11/2022
2.13.0-beta001 262 1/11/2022
2.12.0 352 1/6/2022
2.12.0-beta001 243 1/6/2022
2.11.1 1,488 12/1/2021
2.11.1-beta001 842 12/1/2021
2.11.0 3,312 11/24/2021
2.11.0-beta004 3,247 11/24/2021
2.11.0-beta002 3,261 11/24/2021
2.11.0-beta001 3,169 11/24/2021

- [Moves many functions to inline with InlineIfLambda for performance](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/166) Credits [@TheAngryByrd](https://github.com/TheAngryByrd)