F# Weekly #37, 2026 — F# 11 RC1 and Fantomas 8 Beta Land

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

• F# in .NET 11 RC 1 – Release Notes

F# in .NET 11 RC 1 – Release Notes #fsharp github.com/dotnet/core/…

— Sergey Tihon 🦔🦀 (@sergeytihon.com) 2026-09-12T19:13:06.634Z

Microsoft News

• Announcing .NET 11 Release Candidate 1 – .NET Blog
• Use C# unions and closed hierarchies in ASP.NET Core – .NET Blog
• .NET Conf 2026 Community Days Call for Presenters Is Open – .NET Blog
• Today I will… find hidden latency across a distributed .NET application – Visual Studio Blog
• Your work might not need the smartest model – Microsoft for Developers
• Microsoft Foundry updates: July and August 2026

Videos

• Michal Lusiak – Developer Friendly Machine Learning with F# – NewCrafts 2018
• .NET Unboxed: .NET 11 Release Candidate 1!!
• Working With Your Data, Safely: Files, Approvals and Memory

Blogs

• Worse is better: C# versus F# – Mark Seemann
• .NET 11 reaches its first release candidate! – Aptivi

Announcing .NET 11 Release Candidate 1

— ErikEJ (@erikej.bsky.social) 2026-09-10T07:22:01.022Z

Highlighted projects

• fs-fio/fio: 🪻 A Type-Safe, Purely Functional Effect System for F#
• serde-fs/Serde.FS: A deterministic, reflection‑free serialization and RPC platform for F#. Powered by Serde‑style source generation for .NET and (soon) Fable.
• fsprojects/fantomas: FSharp source code formatter

New Releases

• SageFs 0.6.483
• Pulsar.Client 3.19.1
• Fable 5.17.1
• Fun.Build 1.2.0
• FsLexYacc 12.0.0
• fsharp-analyzers 0.39.1
• Fable.Compiler 5.16.1
• Fabulous 10.0.1
• SqlHydra.Query 5.0.0
• Facil 3.2.0
• Fable.Python 5.5.0
• SqlHydra.Cli 5.0.0
• FSharp.HotChocolate 1.0.3
• WoofWare.Myriad.Plugins 11.0.6
• Xake 3.3.0.20
• FAkka.FSharp.Collections.ParallelSeq 10.1.400
• linq2db.FSharp 6.5.0
• FAkka.Chiron 10.1.400
• HeterogeneousCollections 1.1.7
• Oxpecker.Htmx 4.0.0
• ShapeSifter 1.1.30
• Str 0.24.1
• FsLangMcp 0.18.0
• Mibo.Templates 5.0.0
• FsLex.Core 12.0.0
• CommandTree 0.10.1
• Earcut 3.2.33
• fsharp-refactor 0.8.11
• FsLiveDocs 0.6.2
• Orleans.FSharp.Runtime 5.0.1
• ResizeArrayT 0.27.0
• Orleans.FSharp 5.0.1
• ArrayT 0.26.1
• zest 0.7.3
• ModeMath 0.16.0
• Dicts 0.5.1
• FunStripe.Core 2.4.0
• Summatic.FSUtils 0.6.0
• Axial 0.9.1
• HsSqlAgent.SqlCore 2.0.5
• Klip 3.1.1
• Fason 0.8.0
• Kookerella.FsOpenXmlDsl 0.3.2
• Feather.Cache 1.0.1
• Partas.FSharp.Data.JsonSchema.Core 3.1.3
• Hawaii5O 0.71.1
• SvgPath 1.0.0
• Beforeguard.Frostline.WoW 0.4.0
• FunGoo 0.3.0
• Euclid.BVH 0.1.0
• FunGoo.Widgets 0.3.0
• fsxpired 0.1.0
• FSharp.Data.YamlValue 0.1.1
• fantomas 8.0.0-beta-003

Fantomas 8 is ready. The beta is the final validation window. Test it on your project and tell me about bugs, regressions, or breaking changes that genuinely do not work. Once stable, the intentional changes are committed and consumers should migrate.#fsharp

— Florian Verdonck (nojaf) (@verdonckflorian) September 9, 2026

That’s all for now. Have a great week.