DC Systems for September is next Tuesday, September 8! Come see Tom Barber talk about Killing the Cluster: Replacing Spark with Polars in a Pipeline That Ships to Places You Can't SSH Into and Stephen Goguen tell you Why You Should Reinvent Enumerative Property-Based Testing luma.com/367gihfe
DC Systems 2026-09 · Luma
https://dcsystems.xyz/ DC Systems is an independent tech talk series focused on systems programming here in DC and the broader DMV area. We're focused on high…
luma.com
if anyone is looking for a distraction... you could formalize your typescript.
Steve Goguen@sgoguen.bsky.social · 3w agoI understand you’re likely not trying to literally formalize React itself, but to distill and prove the essential qualities in Lean. However, can I suggest an interesting distraction by suggesting you look at LemmaScript? lemmascript.org
Came across this F# like language that compiles to Python. It includes Active Patterns, Computation Expressions and units of measure in an early release. simontreanor.github.io/Pyfun/
Introduction - Pyfun
Learn Pyfun: functional programming for the Python ecosystem.
simontreanor.github.io
My first book is out this week, The Proof in the Code. Two notes: 1. It's a character-driven story about people who dared to envision a new way of doing mathematics. 2. I can still barely believe the perfect confluence between Lean and our AI moment. www.quantabooks.org/books/the-pr...
The Proof in the Code - Quanta Books
The inside story of Lean, a computer program that answers the age-old question: How do you know if something is true?
quantabooks.org
Very happy and excited to announce that Serde.FS beta.1 now supports Fable 5 as an RPC client! One `[<RpcApi>]` interface gets you ASP.NET routes, a typed .NET client, AND a typed Fable 5 browser client. Generated codecs. No reflection. github.com/serde-fs/Ser... #fsharp @sergeytihon.com
"Normal" people are not disgusted by teh transes. Normal people hope for the best for us, like they would for anyone. Normal people are kind. Kindness is normal. The present apartheid is being conducted by people with levels of unkindness that are not normal for human beings. It is venom.
Reasonable set = representable axioms Gödel never proved *shit* about unrepresentable axioms 😜
Quanta Magazine@quantamagazine.org · 4mo agoKurt Gödel established that for any reasonable set of mathematical axioms, it’s impossible to prove that they won’t eventually lead to contradictions. This meant that mathematicians could never again be certain that their rules were self-consistent. www.quantamagazine.org/how-unknowab...
The entire software industry has had to make the decision “Fast, cheap and good: pick two” when it comes to AI and FAST & CHEAP has won in a landslide. The debate is now more about how good you can get it when you’re producing code faster than you can read or asking how bad are a few bugs anyway?
My university has a fund for post-docs coming from abroad! If you are interested in working with me & our group on something related to programming systems and languages, from PL, HCI or historical & philosophical perspectives, get in touch (ideally in a few days...) See: cuni.cz/UKEN-178.html
Junior Fund
cuni.cz
ML researchers know Python. Proof engineers know Lean. Never the two should meet.. Until now! Announcing Lean.py, effortless Lean to Python and Python to Lean bindings! - Write Lean tactics in Python - Access the Python ecosystem in Lean github.com/kiranandcode...
![/-- Expr-based equality check. Receives `Lean.Expr` trees (via the
`derive_python` Reflect registration) and delegates conversion entirely
to Python's `lean_to_sympy` module. -/
@[python "sympy_expr_eq_accept"]
def sympyExprEqAccept (lhs rhs : Lean.Expr) : IO Bool := do
init ()
let mod ← import_ "lean_to_sympy"
let checkFn ← mod.getAttr "sympy_eq_check"
let convFn ← mod.getAttr "expr_to_sympy"
let lhsSy ← convFn.call #[← Py.ofLeanObj lhs]
let rhsSy ← convFn.call #[← Py.ofLeanObj rhs]
(← checkFn.call #[lhsSy, rhsSy]).toBool](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:i32jjsch6xqcguzsf2lgbfyu/bafkreidjowsbwstojoc67hyrxgolgekqqduzv5afwd3wfrg4sr4lqvhpgm)
Kiran@kirancodes.me · 4mo agoPython and lean are the same language right? (this is lean code that is manipulating Python numpy objects)
![def runDemo : IO Unit := do
IO.println "demo_run:"
let a <- NDArray.ones .f64 [3, 4]
let b <- NDArray.ones .f64 [4, 2]
let c <- NDArray.matmul a b
let d <- NDArray.reshape c [6]
IO.println s!" {<- d.repr}"
#eval runDemo](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:i32jjsch6xqcguzsf2lgbfyu/bafkreieycwm352l4xweu5jzffnk54j255nqexcepx3mqnuhs37amap3kra)
I just noticed that the Wikipedia page on AUTOMATH is not very good at all. It's too short, often wrong and has no examples. I could contribute to a proper page but I would not want to be the sole author. Anyone else want to help?
The Zig project's rationale for their blanket ban on AI-assisted contributions makes a lot of sense to me - for them, time spent reviewing PRs isn't about the code, it's about growing new contributors for the future of the project simonwillison.net/2026/Apr/30/...
The Zig project's rationale for their firm anti-AI contribution policy
Zig has one of the most stringent anti-LLM policies of any major open source project: No LLMs for issues. No LLMs for pull requests. No LLMs for comments on the …
simonwillison.net
✨Fable v5 ✨ Such great news today ❤️ In addition to JS/TS, Rust, and Dart, the Python target has been significantly improved, and there is also the exciting new BEAM target added to the list. Write once run everywhere 🥰 #fsharp #fablecompiler
Maxime@mangelmaxime.bsky.social · 5mo agoFable 5 has been released 🎉 This is the result of almost 1 year and a half of work from the community and the maintainers. Huge thank you to everyone involved. ❤️ #fsharp #fablecompiler
From mid-April I'll be back on the market looking for work. - 25+ years professional experience. - .NET since the start, Node 3+ years. - See mikehadlow.com/top/about/ for details. - Contract or perm. Slight preference for contract. - Must be remote. (I'm UK based).
The greatest bamboozle that the English language ever pulled is using the same word for legal rights and actual rights. The second-greatest is using the same word for proof-objects and actual proofs
Perhaps not too impressive for now but this shows Giraffe (F#) running on the BEAM (Erlang Runtime) using Fable (WIP) #fablecompiler #fsharp
I almost never post about agentic AI stuff because I feel like most of it is overhyped ungrounded trash. Having personally played with F* and LLMs together, I’m both encouraged and not surprised by Nikhil’s early progress using LLMs to build verified software. risemsr.github.io/blog/2026-02...
Agentic Proof-Oriented Programming
Exploring AI-assisted proof-oriented programming with Copilot CLI and F*.
risemsr.github.io
Placing a layer of algorithmic recommendation on speech does not make speech less free, but it does pervert it. Algorithmic mediation turns speech into a resource extracted from human behavior. Platforms do not value speech because it is protected, they value the service it provides them.
Here's a tragedy of DOGE that most people will never know about, even though it has big consequences: no one is left to coordinate the transition to memory safe systems code. 🧵
Andrew Lilley Brinker@alilleybrinker.com · 9mo ago"Memory Safety for Skeptics," published in the ACM Queue. Arguing for why memory safety is worth pursuing, even amid competing priorities and limited budgets, and with or without Rust.
My FS Advent post for Dec 22, 2025. 🎄✨☕ Thanks to @sergeytihon.com for keeping the F# community buzzing along year after year! jordanmarr.github.io/fsharp/cloud... #FsAdvent #fsharp
Create a Cloudflare Worker in .NET?!
A blog about F#, Fable, and functional programming in .NET
jordanmarr.github.io
My F# Advent Calendar post about Fable.Python (and ended up with Fable.Literate 🙈). Learn how you can use Pydantic, FastAPI with Fable 🐍🦔 cardamomcode.dev/fable-python #FsAdvent #fsharp #fablecompiler #python
Fable Python
Introduction to Fable.Python This post is part of the F# Advent Calendar 2025. Thank you, Sergey Tihon, for organizing this wonderful tradition that brings the F# community together every year! Welcome to this guide on Fable and Fable.Python - a co...
cardamomcode.dev
Reboosts welcome! Any UK academics able to host me for 1–2 weeks in January while my visa processes? I am a researcher in programming languages and formal methods, working on proof maintenance on interactive and automated verification tools. Happy to give a talk & collaborate. kirancodes.me
Kiran's home page~ - To Proof Maintenance for all and beyond!!!
kirancodes.me
I love posts/papers that review this history and I implore more people working in this field to share their perspectives and contributions to this amazing and very diverse practice. Future generations need to understand how ambitious & rich these last 50 years have been. Please share your stories!
Lawrence Paulson@lawrpaulson.bsky.social · 9mo agoNew on my blog: 50 years of proof assistants lawrencecpaulson.github.io/2025/12/05/H...
For this year's #fsharp #FsAdvent, I'm announcing a preview of a .NET testing library I'm calling DenseCheck. DenseCheck is a systematic alternative to QuickCheck/FsCheck's random tester. Like FsCheck, DenseCheck automatically generates values from types! github.com/sgoguen/Dens...
github.com
F# Weekly #47, 2025 - F# 10 & last #FsAdvent slots #fsharp sergeytihon.com/2025/11/22/f...
F# Weekly #47, 2025 – F# 10 & last #FsAdvent slots
Welcome to F# Weekly, A roundup of F# content from this past week: News Introducing F# 10 – .NET Blog Introducing C# 14 – .NET Blog Introducing Major New Agentic Capabilities for GitHub…
sergeytihon.com
