dotnet/AspNetCore.Docs

Support F# `Async<'T>` as an awaitable type in minimal APIs

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#31,140 opened on Nov 27, 2023

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Description

I'm opening this as a placeholder to ensure that the changes from https://github.com/dotnet/aspnetcore/pull/46898 make it into the release notes for 9.0. See also: https://github.com/dotnet/aspnetcore/issues/46773.

I see that 8.0 had #28596, so this issue should be linked to the equivalent for 9.0, if there ends up being one.

Additions

  • Support F# Async<'T> as an awaitable type in minimal APIs endpoints.

Changes

  • New runtime coercions: unit ⇝ void, when unit is the generic type argument of a generic awaitable type. These coercions apply both to minimal APIs endpoints as well as to controller action methods.

    • Task<unit> → Task
    • ValueTask<unit> → ValueTask
    • Async<unit> → Task

    With default serialization settings, endpoints with the return types Task<unit> or ValueTask<unit>, whose response body was formerly the JSON token null, will now return an empty response body instead.

EDIT by @Rick-Anderson to add the following metadata

Page URL

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis?view=aspnetcore-9.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/fundamentals/minimal-apis.md

Document ID

b09824ab-b051-75a1-13b7-b0e281cc46e0

Article author

Rick-Anderson

Associated WorkItem - 186857

Contributor guide

Tech stack
csharp
Domain
documentationapi
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with ASP.NET Core minimal APIsBasic knowledge of F#Understanding of release notes structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the linked PR (dotnet/aspnetcore#46898) and issue #46773 to understand the changes. Locate the release notes file for ASP.NET Core 9.0 in the docs repository. Add an entry documenting that F# Async<'T> is now supported as an awaitable type in minimal APIs, including the new runtime coercions from unit to void. Ensure the entry matches the existing style and format of release notes.
Support F# `Async<'T>` as an awaitable type in minimal APIs · dotnet/AspNetCore.Docs#31140 | Good First Issue