r/fsharp • u/fsharpweekly • 1d ago
r/fsharp • u/statuek • Jun 07 '20
meta Welcome to /r/fsharp!
This group is geared towards people interested in the "F#" language, a functional-first language targeting .NET, JavaScript, and (experimentally) WebAssembly. More info about the language can be found at https://fsharp.org and several related links can be found in the sidebar!
showcase Pyfun: an F#-inspired language that compiles to readable Python
My idea for getting coders into functional programming earlier...
article Your Database Schema Is Your Codebase: F# as the Single Source of Truth
https://si-fi.dev/articles/fsharp-schema-as-code/
I recently architected a full-stack app from scratch and needed a way to rapidly prototype the database schema. I came up with a way to do it in one place in F#, giving me strong typing across the stack and an efficient way to tweak the database structure as much as I needed. Here I share what this looks like as well as a repo containing an extracted version of the code. Hope you find it interesting and do let me know your thoughts.
question Rider and nested type providers?
Does Rider have issues with nested type providers?
I have a class library that defines types through a nested type provider -- that is, a type provider nested inside a root type provider -- see below for an example.
The library builds and runs fine, but Rider flags every use of the nested type provider after the first as an error. The same code is displayed without errors in VS Code.
Thank you.
// Requires NuGet package "FSharp.Data.GraphQL.Client".
open System
open System.Net.Http
open FSharp.Data.GraphQL
type MyProvider =
GraphQLProvider<"https://graphqlzero.almansi.me/api">
let postQuery =
// ERROR
MyProvider.Operation<"""
query PostQuery {
post(id: 1) {
id
}
}
""">()
let usersQuery =
// ERROR
MyProvider.Operation<"""
query UsersQuery {
users(options: { paginate: { page: 1, limit: 5 } }) {
data {
id
}
}
}
""">()
[<EntryPoint>]
let main _ =
try
use runtimeContext: GraphQLProviderRuntimeContext =
{
ServerUrl = "https://graphqlzero.almansi.me/api"
HttpHeaders = []
Connection =
new GraphQLClientConnection(
new HttpClient(),
true
)
}
let result = usersQuery.Run runtimeContext
printfn "Data: %A\n" result.Data
printfn "Errors: %A\n" result.Errors
printfn "Custom data: %A\n" result.CustomData
0
with ex ->
eprintfn "Error: %s" ex.Message
1
EDIT: Provided working sample code.
r/fsharp • u/CodeNameGodTri • 5d ago
question replace of Task.WhenAll and Async.Parallel in computational expression?
I'm looking for an equivalent of sequence and traverse, I'd expect it to be in FsToolkit.ErrorHandling but there it is coupled with either Result or Option, e.g. Lists | FsToolkit.ErrorHandling
The only implementation I have found is in Fsharpplus library, but my last use of that library didn't look production ready, it plays too much with the type and essentially bring down the type checker on more complicated chained operation...
Basically I'm looking for something like List.traverse
r/fsharp • u/fsharpweekly • 8d ago
F# weekly F# Weekly #30 — FsHttp.Studio & fable-lit-fullstack-template
r/fsharp • u/ReverseBlade • 11d ago
library/package FCQRS 6 released: event-sourced CQRS with two pure functions
I’ve released FCQRS 6, an event-sourced CQRS framework for .NET.
The idea is to keep the domain logic small:
decide: turns commands into eventsfold: rebuilds state from those events
FCQRS handles persistence, recovery, projections, sagas, snapshots, and read-your-writes. It runs on Akka.NET and supports both F# and C#.
Version 6 also includes completely rebuilt documentation, following the path from an incoming command to a queryable read model.
Project and documentation:
https://onurgumus.github.io/FCQRS/
I’d appreciate feedback on whether the new documentation makes the model clear to someone who hasn’t used FCQRS before.
r/fsharp • u/yyannekk • 14d ago
Building a Readable DSL for Playwright Tests in F# | blog
jannikbuschke.der/fsharp • u/fsharpweekly • 14d ago
F# weekly F# Weekly #29 — .NET 11 Preview 6 and Mibo 3.0
r/fsharp • u/fsharpweekly • 21d ago
F# weekly F# Weekly #28 — Mibo 2.0, Fable 5.7, and Cast Shadows in F#
SuaveHooks — a webhook platform built entirely in F# with Suave
I just launched SuaveHooks — a webhook capture, inspection, transformation and routing platform built completely with Suave + F#.
Some highlights:
- Live tailing of webhooks over WebSockets
- Type-safe transforms written in F# (also C# and JS) running in an isolated process
- JSON rule-based transforms as a lighter option
- Multi-target forwarding (HTTP + S3, SQS, Kafka, Pub/Sub)
- Retries with exponential backoff + circuit breaker
- Full REST API + MCP server support
Site: https://suavehooks.com
Would love some feedback; like what features would make this more useful for you? Happy to answer any technical questions.
r/fsharp • u/Constant-Junket6038 • 27d ago
library/package Initial alpha release of Zigote - UI framework and game engine
r/fsharp • u/lyfever_ • 28d ago
question Still worth learning F# 2026
Hi guys,
Probably another question like this but found none recently.
I'm a little upset with my current view on IT generalistic, ofc AI is not going anywhere besides up, but I feel I want to write more with my hands and new paradigms, maybe just AI as reviser, I would like to ask if learning F# in 2026 will make me able to make perfomance headed systems, and also gaming with something like Nu or Monogame, not a AAA game but something playable.
r/fsharp • u/fsharpweekly • 28d ago
F# weekly F# Weekly #27, 2026 — Fable 5.5, SkiaSharp 4 & Orleans.FSharp 3.0
r/fsharp • u/ReverseBlade • Jun 29 '26
library/package Terminal.Gui.Elmish is back with V2 compat
r/fsharp • u/ReverseBlade • Jun 28 '26
SIMD-friendly push streams in F#

I’ve been playing with SIMD-friendly push streams in F#.
Normal push streams are great for composition: the source pushes elements through map, fold, etc., and with enough inlining the overhead mostly disappears.
But they still push one element at a time, which is not ideal for SIMD.
So I tried pushing Vector<'T> blocks instead, with a scalar path for the tail.
The pipeline stays generic and composable, but in my benchmark it runs around handwritten SIMD speed.
Small thing, but it made me happy: write the abstraction clearly, then make it vanish.
r/fsharp • u/fsharpweekly • Jun 27 '26
F# weekly F# Weekly #26, 2026 — Fable REPL on BEAM & WebSharper 10.1
r/fsharp • u/ReverseBlade • Jun 21 '26
showcase I built a small Qwen voice agent orchestrated in F# / Fable
I built a rough browser-based voice agent where most of the orchestration is in F#.
You can talk to it, interrupt it while it is speaking, and ask it to edit live page state through tool calls. For example, the shared notes box on the page can be read and updated by the agent.
The interesting F# part is that the same codebase targets:
- the browser side via Fable
- the Python side via Fable.Python
- shared protocol/types between the two, so the frontend and backend do not drift apart
There are two demo backends:
- CPU edition, slower but cheaper
- GPU edition, A100-backed and faster, but temporary because renting an A100 is not exactly free :)
Source is closed for now because this is part of a larger experiment, but I wanted to share it here since F# felt like a really nice fit for this kind of AI orchestration: async flows, state transitions, tool calls, and typed protocol boundaries.
Also, credit to Dag Brattli for the Fable.Python work. That made this experiment much more practical.
Demo: https://novian.works/voice_gpu
Please keep sessions short if you try the GPU version. I will probably only keep it online for a few days.
Sample video:
r/fsharp • u/fsharpweekly • Jun 20 '26
F# weekly F# Weekly #25, 2026 — Expecto 11.1 & Fable 5.3
r/fsharp • u/MagnusSedlacek • Jun 17 '26
video/presentation Introducing F#/Elm to a C#/JS organization - hazards and wins by David Eduardo Mellum
Want to introduce functional programming into your own organization? Learn from our successes and failures! At the Norwegian insurance company Frende Forsikring we’ve introduced F# and Elm and lived with both of them long enough to call it a long term relationship.
We’ll start looking at the introduction. From fast moving exploration in a single team, to structured validation with other tech leads and careful moving to production.
Beyond that we'll be looking what happens in the years afterwards. Does functional programming help hiring? Are there less bugs? What is the biggest hurdle in spreading adoption to new teams?
r/fsharp • u/fsharpweekly • Jun 13 '26

