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Jordan Marr

@jordanmarr.bsky.social

Spreading the gospel of F# https://github.com/JordanMarr

363 Followers  |  189 Following  |  111 Posts  |  Joined: 12.11.2024
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Posts by Jordan Marr (@jordanmarr.bsky.social)

Not exactly. SourceDjinn came out of the internals I built for Serde.FS to get that "attribute-and-go" C# source generator experience.
Myriad definitely influenced the direction, though β€” you really can’t think about F# metaprogramming without thinking of Myriad!

03.03.2026 20:56 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Fable Β· Announcing Fable 5 Release Candidate

The wait is over! Fable 5 Release Candidate is officially here.

After a year of hard work from the community, we're bringing you:
✨ .NET 10 & F# 10 support
🐍 A massive Python update (now powered by a Rust core & PyPI!)
🌐 Cleaner JS/TS Pojo bindings

fable.io/blog/2026/20...

#fsharp #fablecompiler

03.03.2026 17:18 β€” πŸ‘ 34    πŸ” 12    πŸ’¬ 4    πŸ“Œ 0

Serde.FS.Json is the first backend in the new Serde.FS ecosystem β€” fast, reflection‑free JSON for F#.

Powered by FSharp.SourceDjinn, a small engine for building F# source generators.

github.com/fs-djinn
#fsharp

03.03.2026 15:04 β€” πŸ‘ 15    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0

As for ecosystem size, I think this may be the golden era for F# because the people using it do so because we love the language. We like making OSS projects for it, and it's now easier than ever for the community to create awesome stuff for the F# ecosystem -- which is exactly what is happening now.

26.02.2026 15:15 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

I do all my work in F# and still get the warm glow. Simple functions as DSLs + small interim types allows me to design declarative workflow-specific pipelines that would be imperative in other langs. But as you move away from the code, perhaps it doesn't matter.

26.02.2026 15:15 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
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Release SqlHydra v3.5.0 Β· JordanMarr/SqlHydra SqlHydra.Query 3.5.0 New Feature: SQL Server Upsert (insertOrUpdateOnUnique) SqlHydra.Query now supports insert-or-update (upsert) for SQL Server via the new insertOrUpdateOnUnique custom operation...

SqlHydra v3.5 released with new query functionality for SQL Server. #fsharp

github.com/JordanMarr/S...

23.02.2026 18:04 β€” πŸ‘ 7    πŸ” 1    πŸ’¬ 0    πŸ“Œ 0

Well-articulated points.

Opus 4.6 is a savant junior coder. I just watched it try to add an `Errors` property to my response -- completely ignoring the fact that the function was wrapped in an `asyncResult` CE. πŸ€¦β€β™‚οΈ

16.02.2026 19:08 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Around 3 Years later but Migrondi v1 release is out!

#dotnet #fsharp #migrondi

10.02.2026 21:51 β€” πŸ‘ 4    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0
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Release v2.1.0 Β· JordanMarr/FSharp.SystemCommandLine ✨ New: First‑class dependency injection with Input.inject Input.inject now allows you to pass runtime dependencies (loggers, configuration, services, etc.) directly into your command actions as fir...

FSharp.SystemCommandLine v2.1 provides a more declarative way to inject services alongside CLI arguments and options.

github.com/JordanMarr/F... #fsharp

08.02.2026 21:17 β€” πŸ‘ 7    πŸ” 2    πŸ’¬ 1    πŸ“Œ 0

I've always said that "typing is not the bottleneck."
Thinking through the problem, use cases, edge cases and designing invariants is.

03.02.2026 14:57 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Release SqlHydra v3.3 + v3.4 Β· JordanMarr/SqlHydra An ergonomic release that modernizes how query contexts are created, improves left‑join projections, and introduces a more expressive join API. Fully backward‑compatible with 3.2, and forward-looki...

SqlHydra - v3.4 is out today. It is a rollup of the last two releases. Lots of nice, new features and some deprecated ones to help transition into an upcoming v4.0. #fsharp

github.com/JordanMarr/S...

03.02.2026 14:46 β€” πŸ‘ 8    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0
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GitHub - JordanMarr/fable-lit-fullstack-template: A SAFE-style template with Fable.Lit, Fable.Remoting and Giraffe A SAFE-style template with Fable.Lit, Fable.Remoting and Giraffe - JordanMarr/fable-lit-fullstack-template

Big update for the Fable + Lit ecosystem!

✨ Fable.Lit.Dsl
✨ Fable.Lit.Dsl.Shoelace
✨ Fullstack template update (.NET 10 + Fable 5)

#fsharp #webcomponents #lit
github.com/JordanMarr/f...

27.01.2026 00:43 β€” πŸ‘ 20    πŸ” 9    πŸ’¬ 0    πŸ“Œ 0
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Releases Β· JordanMarr/Agent.NET A composable AI agent framework for .NET. Contribute to JordanMarr/Agent.NET development by creating an account on GitHub.

πŸš€ Agent.NET has evolved significantly since the alpha.1 announcement β€” alpha.2 and now alpha.3 bring proper MAF execution, symmetrical InProcess/Durable workflows, and a more cohesive workflow CE with ROP built in.

Full release history:
github.com/JordanMarr/A...

#fsharp #dotnet #aiagents

21.01.2026 16:46 β€” πŸ‘ 13    πŸ” 3    πŸ’¬ 0    πŸ“Œ 0
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It's kind of funny that due to AI/LLMs these days another metric to rate #programming languages on has become "token efficiency".
On the bright side - some of the beloved languages like #Clojure, #Ruby, #FSharp and #OCaml fared pretty well due to their expressive and compact syntax.

16.01.2026 09:29 β€” πŸ‘ 23    πŸ” 13    πŸ’¬ 3    πŸ“Œ 0
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GitHub - JordanMarr/Agent.NET: A composable AI agent framework for .NET. A composable AI agent framework for .NET. Contribute to JordanMarr/Agent.NET development by creating an account on GitHub.

github.com/JordanMarr/A...

05.01.2026 06:11 β€” πŸ‘ 2    πŸ” 1    πŸ’¬ 0    πŸ“Œ 0
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A beautiful F# library for building AI agents on .NET:

β€’ Quotation-based tool discovery
β€’ Pipeline-style agent composition
β€’ Computation expressions for workflows
β€’ Railway-oriented error handling

F# deserves a place in the agent era β€” and this is my contribution.

#fsharp #dotnet

05.01.2026 06:11 β€” πŸ‘ 13    πŸ” 3    πŸ’¬ 2    πŸ“Œ 0
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Release SqlHydra v3.2.0 Β· JordanMarr/SqlHydra SqlHydra.Query Built-in SQL Functions Use SQL functions directly in your queries with full type safety! Each database provider includes a SqlFn type with common functions. open SqlHydra.Query open ...

SqlHydra v3.2 big release today that builds on yesterday's release! Now includes DB-specific functions for all 5 supported DBs, custom functions, and adds .NET 10 support.
Samples included in the release notes.

github.com/JordanMarr/S... #fsharp

23.12.2025 19:13 β€” πŸ‘ 5    πŸ” 1    πŸ’¬ 0    πŸ“Œ 0
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Release SqlHydra.Query v3.1.0 Β· JordanMarr/SqlHydra Support for SQL Functions You can now call custom functions supported by your database: open SqlHydra.Query // Create DB function stubs: let SUBSTRING (s: string, start: int, length: int) : string...

SqlHydra.Query v3.1.0 adds support for calling SQL functions!

github.com/JordanMarr/S... #fsharp

23.12.2025 04:47 β€” πŸ‘ 9    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0
Create a Cloudflare Worker in .NET?! A blog about F#, Fable, and functional programming in .NET

My FS Advent post for Dec 22, 2025. πŸŽ„βœ¨β˜•

Thanks to @sergeytihon.com for keeping the F# community buzzing along year after year!

jordanmarr.github.io/fsharp/cloud... #FsAdvent #fsharp

22.12.2025 17:38 β€” πŸ‘ 13    πŸ” 3    πŸ’¬ 1    πŸ“Œ 0
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Sneak peek of new #fsharp side project...

Fable + Desktop πŸ€”

22.12.2025 15:46 β€” πŸ‘ 69    πŸ” 6    πŸ’¬ 2    πŸ“Œ 1

All day, every day!

19.12.2025 15:22 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

I don’t notice much difference between my F# and C# project build times.
But I’ve heard some type provider libraries can slow it down though.

14.12.2025 19:24 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Great tips for getting real value out of FSI! I love the idea of creating bootstrap fsx scripts to preload modules. That alone will make FSI much more useful for non-trivial exploration.
And the MCP server obviously takes it to the next level as well.

14.12.2025 16:08 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Frogs ’n Flies was straight up my favorite Atari game back in the day!

If you hit the expert mode switch on the console, you could very precisely control your frog’s jump!

Bringing it back full circle in 2025 with the FP FrogInterpreter! ❀️🐸

12.12.2025 16:02 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Mark Seemann did a great talk years ago where he showed examples of some really gnarly method headers in C# to emphasize how type inference is almost a requirement for FP.
Would love to watch it again if I could find it.

10.12.2025 16:56 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

Right?! Even though β€œC# has all the FP features from F#”, not having type inference makes things that are trivial in F# so ugly in C# that most will never use it.

10.12.2025 16:51 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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t really bothers me having to type in the full tuple return type and predicate function type in C#.

To each their own but #fsharp type inference just makes me happy.

10.12.2025 00:13 β€” πŸ‘ 15    πŸ” 1    πŸ’¬ 2    πŸ“Œ 0

Fable 4 and Fable 5, both got a new release to make them work with .NET 10 πŸŽ‰ #fsharp #fablecompiler

25.11.2025 22:19 β€” πŸ‘ 36    πŸ” 6    πŸ’¬ 3    πŸ“Œ 0

That seems like it could work pretty well. I would think that giving it an example bindings project with a style that you like and then pointing it to API docs could work pretty well.

25.11.2025 16:52 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

F# 9 added support for "Nullable Reference Types" (which is not on by default!). This will indicate when core .NET BCL methods return types with the nullable annotation as a warning / error.

25.11.2025 16:48 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0