FsToolkit.ErrorHandling.IcedTasks 5.0.0-beta014
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
- The main resource as to learning this style of programming Railway Oriented Programming
- However Result isn't a panacea, see what pitfalls and where you shouldn't use
Result. In defense of Exceptions: Throw (away) your Result
Builds
| GitHub Actions |
|---|
 |
NuGet
| Package name | Release | Prelease |
|---|---|---|
| FsToolkit.ErrorHandling | ||
| FsToolkit.ErrorHandling.TaskResult | ||
| FsToolkit.ErrorHandling.JobResult | ||
| FsToolkit.ErrorHandling.AsyncSeq | ||
| FsToolkit.ErrorHandling.IcedTasks |
Developing locally
Devcontainer
This repository has a devcontainer setup for VSCode. For more information 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 projectsbinandobjfoldersDotnetTest- Will run tests fordotnetprojectsNpmTest- Will run tests forfable-javascriptprojectsPythonTest- Will run tests forfable-pythonprojectsRunTests- Will run tests fordotnet,fable-javascriptandfable-pythonprojectsFormatCode- Will runfantomasto format the codebase
This is not an exhaustive 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)
Showing the top 20 packages that depend on FsToolkit.ErrorHandling.IcedTasks.
| Packages | Downloads |
|---|---|
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
14 |
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NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
12 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
11 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
10 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
9 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
8 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
7 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
6 |
|
NBomber
Modern and flexible load testing framework for Pull and Push scenarios, designed to test any system regardless a protocol (HTTP/WebSockets/AMQP etc) or a semantic model (Pull/Push).
|
5 |
- 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
- BREAKING: [Rename returnError to error + documentation](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/311) Credits @tw0po1nt
- [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
- [Add Option.traverseAsync and Option.sequenceAsync](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/298#event-15827853276) Credits @tw0po1nt
- [Add Require and Check helper methods](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/295) Credits @PI-Gorbo
- [Add new AsyncOption APIs and document all its other functions; minor fixes to documentation for Option module](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/307) Credits @tw0po1nt
- [F# 9 support and nullness](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/308) Credits @TheAngryByrd
- [Update IcedTasks 0.11.7](https://github.com/demystifyfp/FsToolkit.ErrorHandling/commit/0a4cc7b3c52efcef47dbc653b00d56ab029bbd01) Credits @TheAngryByrd
- [Add TaskValidation module](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/313) Credits @tw0po1nt
- [feat(Seq.traverse/sequence*)!: Yield arrays](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/310) Credits @bartelink
- [Add ParallelAsync CEs](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/318) Credits @njlr
- [Add Option.sequenceAsyncResult and Option.traverseAsyncResult](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/321) Credits @JayWearsSocks
- [Add traversals/sequences for Task and TaskResult in the Option module](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/325) Credits @tw0po1nt
- [Add ok and error helper functions to TaskResultOption and AsyncResultOption modules](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/327) Credits @tw0po1nt
- [Add CancellableTaskOption module and CE + tests and documentation](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/328) Credits @tw0po1nt
- [Remove paket, Enforce nullness on net9.0, remove mocha](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/331) Credits @TheAngryByrd
- [Add TaskValueOption module, operators, and CE + tests and documentation](https://github.com/demystifyfp/FsToolkit.ErrorHandling/pull/329) Credits @tw0po1nt
.NET 6.0
- FsToolkit.ErrorHandling (>= 5.0.0-beta014)
- IcedTasks (>= 0.11.8)
- FSharp.Core (>= 6.0.4)
.NET Standard 2.1
- IcedTasks (>= 0.11.8)
- FSharp.Core (>= 6.0.4)
- FsToolkit.ErrorHandling (>= 5.0.0-beta014)
.NET Standard 2.0
- Microsoft.Bcl.AsyncInterfaces (>= 6.0.0)
- FSharp.Core (>= 6.0.4)
- IcedTasks (>= 0.11.8)
- FsToolkit.ErrorHandling (>= 5.0.0-beta014)
.NET 9.0
- IcedTasks (>= 0.11.8)
- FSharp.Core (>= 9.0.300)
- FsToolkit.ErrorHandling (>= 5.0.0-beta014)
| Version | Downloads | Last updated |
|---|---|---|
| 5.0.0 | 5 | 06/07/2025 |
| 5.0.0-beta014 | 4 | 06/06/2025 |
| 5.0.0-beta013 | 3 | 06/01/2025 |
| 5.0.0-beta012 | 7 | 05/05/2025 |
| 5.0.0-beta011 | 7 | 04/02/2025 |
| 5.0.0-beta010 | 6 | 03/23/2025 |
| 5.0.0-beta009 | 9 | 03/07/2025 |
| 5.0.0-beta008 | 9 | 03/07/2025 |
| 5.0.0-beta007 | 10 | 02/26/2025 |
| 5.0.0-beta006 | 9 | 02/26/2025 |
| 5.0.0-beta005 | 10 | 02/26/2025 |
| 5.0.0-beta004 | 9 | 02/11/2025 |
| 5.0.0-beta003 | 12 | 01/19/2025 |
| 5.0.0-beta002 | 12 | 01/19/2025 |
| 5.0.0-beta001 | 12 | 12/20/2024 |
| 4.18.0 | 8 | 12/22/2024 |
| 4.18.0-beta001 | 11 | 12/22/2024 |
| 4.17.0 | 10 | 12/22/2024 |
| 4.17.0-beta002 | 8 | 12/22/2024 |
| 4.17.0-beta001 | 11 | 12/22/2024 |
| 4.16.0 | 10 | 12/21/2024 |
| 4.15.3 | 11 | 12/22/2024 |
| 4.15.3-beta001 | 9 | 12/22/2024 |
| 4.15.2 | 11 | 12/21/2024 |
| 4.15.2-beta001 | 8 | 12/22/2024 |
| 4.15.1 | 11 | 12/22/2024 |
| 4.15.0 | 8 | 12/22/2024 |
| 4.14.0 | 8 | 12/22/2024 |
| 4.13.0 | 11 | 12/22/2024 |
| 4.13.0-beta002 | 12 | 12/22/2024 |
| 4.13.0-beta001 | 11 | 12/22/2024 |
| 4.12.0 | 11 | 12/22/2024 |
| 4.11.1 | 11 | 12/21/2024 |
| 4.11.0 | 11 | 12/22/2024 |
| 4.10.0 | 8 | 12/21/2024 |
| 4.9.0 | 8 | 12/22/2024 |
| 4.8.0 | 10 | 12/22/2024 |
| 4.7.0 | 8 | 12/22/2024 |
| 4.7.0-beta001 | 12 | 12/22/2024 |
| 4.6.0 | 11 | 12/22/2024 |
| 4.6.0-beta001 | 9 | 12/22/2024 |
| 4.5.0 | 10 | 12/22/2024 |
| 4.5.0-beta002 | 12 | 12/22/2024 |
| 4.5.0-beta001 | 9 | 12/22/2024 |
| 4.4.0 | 11 | 12/22/2024 |
| 4.3.0 | 9 | 12/22/2024 |
| 4.2.1 | 11 | 12/22/2024 |
| 4.2.0 | 8 | 12/21/2024 |
| 4.1.0 | 11 | 12/22/2024 |
| 4.1.0-beta001 | 12 | 12/22/2024 |
| 4.0.0 | 11 | 12/22/2024 |
| 4.0.0-beta001 | 12 | 12/22/2024 |
| 3.3.1 | 8 | 12/22/2024 |
| 3.3.1-beta004 | 12 | 12/22/2024 |
| 3.3.1-beta003 | 12 | 12/22/2024 |
| 3.3.1-beta002 | 9 | 12/22/2024 |
| 3.3.1-beta001 | 9 | 12/22/2024 |
| 3.3.0-beta001 | 12 | 12/22/2024 |
| 3.2.0 | 11 | 12/21/2024 |
| 3.2.0-beta001 | 12 | 12/22/2024 |
| 3.1.0 | 10 | 12/21/2024 |
| 3.0.1 | 7 | 12/22/2024 |
| 3.0.0 | 11 | 12/22/2024 |
| 3.0.0-beta008 | 8 | 12/22/2024 |
| 3.0.0-beta007 | 11 | 12/22/2024 |
| 3.0.0-beta006 | 12 | 12/22/2024 |
| 3.0.0-beta005 | 11 | 12/22/2024 |
| 3.0.0-beta004 | 12 | 12/22/2024 |