Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation by Copilot · Pull Request #352 · demystifyfp/FsToolkit.ErrorHandling

Copilot · 2026-02-25T02:46:55Z

Add requireSomeWith and requireNoneWith to Result.fs
Add requireSomeWith and requireNoneWith to AsyncResult.fs
Add requireSomeWith and requireNoneWith to TaskResult.fs
Add requireSomeWith and requireNoneWith to JobResult.fs (JobResult project)
Add tests for all four modules
Add gitbook documentation in result/requireFunctions.md
Add gitbook documentation in asyncResult/others.md
Add gitbook documentation in taskResult/others.md
Add gitbook documentation in jobResult/others.md

Original prompt

This section details on the original issue you should resolve

<issue_title>helper to convert option to result with transform</issue_title>
<issue_description>I may have overlooked a helper in either this or the standard library, but I end up finding this function useful, similar to requireSome but where the fallback is evaluated on demand.
let fromOption f = (unit -> 'a) -> option<'b> -> Result<'b,'a> 
      function
      | Some value -> Ok value
      | None -> Error(f ())
Is there an equivalent or would it make sense to add perhaps Result.requireSomeWith?</issue_description>

Comments on the Issue (you are @copilot in this section)
@TheAngryByrd Agreed! Seem like a good PR to have:

Add requireSomeWith and requireNoneWith

Add to Result, AsyncResult, TaskResult, JobResult

Add corresponding tests</comment_new>

Fixes helper to convert option to result with transform #301

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…t, TaskResult, and JobResult Co-authored-by: TheAngryByrd <1490044+TheAngryByrd@users.noreply.github.com>

TheAngryByrd

@copilot add or update gitbook documentation

Co-authored-by: TheAngryByrd <1490044+TheAngryByrd@users.noreply.github.com>

Copilot · 2026-02-25T03:08:45Z

@copilot add or update gitbook documentation

Done in a39b1da. Added requireSomeWith and requireNoneWith entries to:

gitbook/result/requireFunctions.md
gitbook/asyncResult/others.md
gitbook/taskResult/others.md
gitbook/jobResult/others.md

Copilot

Pull request overview

This PR adds lazy evaluation variants requireSomeWith and requireNoneWith to defer error construction until it's actually needed, providing performance benefits when error messages are expensive to compute.

Changes:

Added requireSomeWith and requireNoneWith functions to Result, AsyncResult, TaskResult, and JobResult modules with [<InlineIfLambda>] for zero-cost abstraction
Added comprehensive test coverage for all implementations covering happy path and error path scenarios

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/FsToolkit.ErrorHandling/Result.fs	Core implementation with XML documentation for `requireSomeWith` and `requireNoneWith` functions
src/FsToolkit.ErrorHandling/AsyncResult.fs	Async wrapper delegating to Result module implementations
src/FsToolkit.ErrorHandling/TaskResult.fs	Task wrapper delegating to Result module implementations
src/FsToolkit.ErrorHandling.JobResult/JobResult.fs	Job wrapper delegating to Result module implementations
tests/FsToolkit.ErrorHandling.Tests/Result.fs	Test coverage for Result module with happy/error path tests and integration into test suite
tests/FsToolkit.ErrorHandling.Tests/AsyncResult.fs	Test coverage for AsyncResult module with async test cases and integration
tests/FsToolkit.ErrorHandling.Tests/TaskResult.fs	Test coverage for TaskResult module with task test cases and integration
tests/FsToolkit.ErrorHandling.JobResult.Tests/JobResult.fs	Test coverage for JobResult module with proper `[<Tests>]` attributes and integration

- [Add IAsyncEnumerable support to task computation expressions](#347) Credits @Copilot - [Add `valueTaskValueOption` CE for `ValueTask<'T voption>` computation expressions](#348) Credits @Copilot - [Add `cancellableValueTaskOption` and `cancellableValueTaskResult` CEs for IcedTasks](#349) Credits @Copilot - [Add `Source` overloads to `taskResultOption` CE for interop with `Result`, `TaskResult`, `Option`, `Task`, and `Async`](#351) Credits @Copilot - [Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation](#352) Credits @Copilot - [Add `TaskResult.ofCatchTask`](#353) Credits @Copilot - [Add comprehensive gitbook documentation for all public API surface](#354) Credits @Copilot

- [Add IAsyncEnumerable support to task computation expressions](#347) Credits @Copilot - [Add `valueTaskValueOption` CE for `ValueTask<'T voption>` computation expressions](#348) Credits @Copilot - [Add `cancellableValueTaskOption` and `cancellableValueTaskResult` CEs for IcedTasks](#349) Credits @Copilot - [Add `Source` overloads to `taskResultOption` CE for interop with `Result`, `TaskResult`, `Option`, `Task`, and `Async`](#351) Credits @Copilot - [Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation](#352) Credits @Copilot - [Add `TaskResult.ofCatchTask`](#353) Credits @Copilot - [Add comprehensive gitbook documentation for all public API surface](#354) Credits @Copilot Remove AutoGPT subproject reference

- [Add IAsyncEnumerable support to task computation expressions](#347) Credits @Copilot - [Add `valueTaskValueOption` CE for `ValueTask<'T voption>` computation expressions](#348) Credits @Copilot - [Add `cancellableValueTaskOption` and `cancellableValueTaskResult` CEs for IcedTasks](#349) Credits @Copilot - [Add `Source` overloads to `taskResultOption` CE for interop with `Result`, `TaskResult`, `Option`, `Task`, and `Async`](#351) Credits @Copilot - [Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation](#352) Credits @Copilot - [Add `TaskResult.ofCatchTask`](#353) Credits @Copilot - [Add comprehensive gitbook documentation for all public API surface](#354) Credits @Copilot

- [Add IAsyncEnumerable support to task computation expressions](#347) Credits @Copilot - [Add `valueTaskValueOption` CE for `ValueTask<'T voption>` computation expressions](#348) Credits @Copilot - [Add `cancellableValueTaskOption` and `cancellableValueTaskResult` CEs for IcedTasks](#349) Credits @Copilot - [Add `Source` overloads to `taskResultOption` CE for interop with `Result`, `TaskResult`, `Option`, `Task`, and `Async`](#351) Credits @Copilot - [Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation](#352) Credits @Copilot - [Add `TaskResult.ofCatchTask`](#353) Credits @Copilot - [Add comprehensive gitbook documentation for all public API surface](#354) Credits @Copilot Remove AutoGPT subproject reference

Initial plan

5e1871c

Copilot AI assigned Copilot and TheAngryByrd Feb 25, 2026

Copilot started work on behalf of TheAngryByrd February 25, 2026 02:47 View session

Add requireSomeWith and requireNoneWith helpers to Result, AsyncResul…

98cc8eb

…t, TaskResult, and JobResult Co-authored-by: TheAngryByrd <1490044+TheAngryByrd@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add requireSomeWith helper for Result type~~ Add requireSomeWith and requireNoneWith for lazy error evaluation Feb 25, 2026

Copilot AI requested a review from TheAngryByrd February 25, 2026 02:52

Copilot finished work on behalf of TheAngryByrd February 25, 2026 02:52

TheAngryByrd requested a review from Copilot February 25, 2026 03:05

TheAngryByrd requested changes Feb 25, 2026

View reviewed changes

Copilot started work on behalf of TheAngryByrd February 25, 2026 03:07 View session

Copilot started reviewing on behalf of TheAngryByrd February 25, 2026 03:08 View session

Add gitbook documentation for requireSomeWith and requireNoneWith

a39b1da

Co-authored-by: TheAngryByrd <1490044+TheAngryByrd@users.noreply.github.com>

TheAngryByrd marked this pull request as ready for review February 25, 2026 03:09

Copilot finished work on behalf of TheAngryByrd February 25, 2026 03:09

Copilot AI requested a review from TheAngryByrd February 25, 2026 03:09

Copilot AI reviewed Feb 25, 2026

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TheAngryByrd merged commit 1c6f444 into master Feb 25, 2026
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This was referenced Mar 2, 2026

chore: Bump FsToolkit.ErrorHandling from 5.1.0 to 5.2.0 bartul/imperium#88

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Bump the deps group with 3 updates otsomkalov/otsom.fs#194

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Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation#352

Add `requireSomeWith` and `requireNoneWith` for lazy error evaluation#352
TheAngryByrd merged 3 commits intomasterfrom
copilot/add-require-some-with-helper

Copilot AI commented Feb 25, 2026 •

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Copilot AI commented Feb 25, 2026 •

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