FsToolkit.ErrorHandling.AsyncSeq 4.15.2-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There is a newer version of this package available.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 4.15.2-beta001
                    
NuGet\Install-Package FsToolkit.ErrorHandling.AsyncSeq -Version 4.15.2-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="4.15.2-beta001" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="FsToolkit.ErrorHandling.AsyncSeq" Version="4.15.2-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 4.15.2-beta001
                    
#r "nuget: FsToolkit.ErrorHandling.AsyncSeq, 4.15.2-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@4.15.2-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=4.15.2-beta001&prerelease
                    
Install as a Cake Addin
#tool nuget:?package=FsToolkit.ErrorHandling.AsyncSeq&version=4.15.2-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

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

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 44 9/26/2025
5.1.0-beta001 46 9/26/2025
5.0.1 298 7/12/2025
5.0.0 198 6/2/2025
5.0.0-beta014 145 6/2/2025
5.0.0-beta013 154 5/29/2025
5.0.0-beta012 654 5/1/2025
5.0.0-beta011 196 3/30/2025
5.0.0-beta010 129 3/21/2025
5.0.0-beta009 730 3/5/2025
5.0.0-beta008 120 3/2/2025
5.0.0-beta007 176 2/23/2025
5.0.0-beta006 119 2/21/2025
5.0.0-beta005 126 2/16/2025
5.0.0-beta004 134 2/4/2025
5.0.0-beta003 118 1/6/2025
5.0.0-beta002 121 12/21/2024
5.0.0-beta001 117 12/7/2024
4.18.0 38,375 10/23/2024
4.18.0-beta001 113 10/23/2024
4.17.0 249 9/23/2024
4.17.0-beta002 89 9/23/2024
4.17.0-beta001 107 9/23/2024
4.16.0 473 7/15/2024
4.15.3 182 7/14/2024
4.15.3-beta001 117 7/14/2024
4.15.2 252 5/2/2024
4.15.2-beta001 113 5/2/2024
4.15.1 590 1/15/2024
4.15.0 42,047 1/10/2024
4.14.0 475 1/2/2024
4.13.0 249 12/10/2023
4.13.0-beta002 142 12/10/2023
4.13.0-beta001 121 12/10/2023
4.12.0 194 11/27/2023
4.11.1 185 11/23/2023
4.11.0 177 11/11/2023
4.10.0 216 10/16/2023
4.9.0 2,101 7/10/2023
4.8.0 240 7/7/2023
4.7.0 247 6/21/2023
4.7.0-beta001 190 6/21/2023
4.6.0 2,768 4/20/2023
4.6.0-beta001 173 4/20/2023
4.5.0 1,181 3/27/2023
4.5.0-beta002 178 3/19/2023
4.5.0-beta001 196 3/6/2023
4.4.0 324 2/21/2023
4.3.0 405 1/20/2023
4.2.1 382 12/19/2022
4.2.0 388 12/17/2022
4.1.0 349 12/13/2022
4.1.0-beta001 188 12/13/2022
4.0.0 466 11/19/2022
4.0.0-beta001 216 11/19/2022
3.3.1 41,365 11/19/2022
3.3.1-beta004 203 11/19/2022
3.3.1-beta003 217 11/18/2022
3.3.1-beta002 182 11/18/2022
3.3.1-beta001 207 11/18/2022
3.3.0-beta001 208 11/9/2022
3.2.0 4,606 10/31/2022
3.2.0-beta001 186 10/31/2022
3.1.0 597 10/19/2022
3.0.1 458 10/18/2022
3.0.0 537 10/14/2022
3.0.0-beta008 221 10/14/2022
3.0.0-beta007 9,234 4/15/2022
3.0.0-beta006 249 4/5/2022
3.0.0-beta005 263 4/5/2022
3.0.0-beta004 224 4/5/2022
3.0.0-beta003 238 3/30/2022
3.0.0-beta002 242 2/21/2022
3.0.0-beta001 263 2/21/2022
2.13.0 6,753 1/11/2022
2.13.0-beta001 282 1/11/2022
2.12.0 374 1/6/2022
2.12.0-beta001 267 1/6/2022
2.11.1 1,501 12/1/2021
2.11.1-beta001 860 12/1/2021
2.11.0 3,331 11/24/2021
2.11.0-beta004 3,260 11/24/2021
2.11.0-beta002 3,282 11/24/2021
2.11.0-beta001 3,187 11/24/2021

- [Fix AsyncValidationCE binding against asyncResult](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/260) Credits @1eyewonder