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Tweag by Modus Create

@tweag.io
92 followers 27 following 142 posts

Tweag is the home of specialized engineering and advisory for Modus Create, uniting engineers and researchers to solve complex challenges. With expertise in functional engineering, build systems like Nix, Bazel, and Buck2, and blockchain like Cardano.

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Tweag by Modus Create @tweag.io · 25/09/2026
Seven years later, Nix flakes are still experimental. At #NixCon2026, Tweag’s Valentin Gagarin will explain why he changed his mind about flakes and why he thinks the controversy was never really about the technology itself. 📅 27 September 🕘 09:00–09:45 📍Room A
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Tweag by Modus Create @tweag.io · 24/09/2026
Your coding agent read the instructions an hour ago. Does it still remember them? Victor Nascimento Bakke on tricorder-mcp, the new MCP server for Tricorder, our Haskell dev tool – and why it keeps agents on track in long sessions. tweag.io/blog/2026-09...
tweag.io
Tricorder MCP server: feedback your agent won’t forget
Using Tricorder and its MCP server with coding agents.
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Tweag by Modus Create @tweag.io · 23/09/2026
Sandboxed Nix builds are great. Rebuilding for the 42nd time? Less so. At #NixCon2026, Tweag’s Guillaume Maudoux will talk about Nixception: fast incremental builds without giving up sandboxing, using the same cache inside and outside the sandbox. 📅 26 September 🕝 14:30–15:15 📍Room A
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Tweag by Modus Create @tweag.io · 21/09/2026
A new release of rules_nixpkgs is here 🚀 v0.14.0 adds full support for Bazel 7, support for depending on Nix flakes and FlakeHub-backed packages, and support for export/propagation of package licenses. registry.bazel.build/modules/rule...
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Tweag by Modus Create @tweag.io · 18/09/2026
We’re heading to #NixCon2026. 👋 We’ll be in Kraków from 25–28 September, as a Silver Sponsor. Our engineers will be attending and speaking throughout the event. Working on adopting or scaling Nix? Come and talk to us. #nixcon #nixos
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Tweag by Modus Create @tweag.io · 17/09/2026
Liquid Haskell can prove your type class laws with an SMT solver – or could, until GHC 9 broke it. Juan Pablo Yamamoto spent #GSoC bringing it back. Here's how it went: tweag.io/blog/2026-09... #Haskell
tweag.io
Restoring type class support in Liquid Haskell
An internship experience report on reenabling type class support in Liquid Haskell
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Tweag by Modus Create @tweag.io · 10/09/2026
@aspiwack.bsky.social specified a tiny SAT solver in Rocq and let a coding agent write the code and proofs. Once the agent stopped duplicating his entire program to dodge a proof, one question remains: Are we formal proofs yet? tweag.io/blog/2026-09...
tweag.io
Are we formal proofs yet? On formal proofs of programs with coding agents
An experiment in constraining coding agent output with formal proofs
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Tweag by Modus Create @tweag.io · 12/08/2026
Tricorder 0.2.0.0 is now available, introducing a quick way to evaluate Haskell expressions directly from comments. Add `-- $> 2 + 2` anywhere in your source code and Tricorder will evaluate it, with the output available in `tricorder ui` and `tricorder eval-comments`.
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Tweag by Modus Create @tweag.io · 23/07/2026
Please follow us as we rewind five years to our very first Cardano smart contract audit. In this retrospective, Mathieu Montin shares the story and lessons behind those five years. www.tweag.io/blog/2026-07...
tweag.io
Five years of Cardano smart-contract audits: a retrospective
A retrospective on five years and twenty-plus Cardano smart-contract audits at Tweag.
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Tweag by Modus Create @tweag.io · 11/07/2026
The Diff package adopts LiquidHaskell! The documentation of Diff was revamped and some of it is now checked automatically, with more static checks coming. Great work by Xavier Góngora. Check✅it out! discourse.haskell.org/t/diff-packa...
discourse.haskell.org
Diff package adopts LiquidHaskell for static checks
Hello, dear haskellers! I want to make a splash about LiquidHaskell being used for static checks in the Diff package, used transitively by more than 17000 packages according to hackage-revdeps [link]...
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Tweag by Modus Create @tweag.io · 09/07/2026
🌳 Topiary now supports Language Injections, formatting "forests" of syntax trees embedded in one another—OCaml inside OCamllex, Rust/JSON blocks inside Markdown—without breaking the host layout. Read all about how we leveraged Tree-sitter to make this happen: www.tweag.io/blog/2026-07...
tweag.io
Topiary: Formatting Forests
How Topiary can now format embedded languages in OCamllex and Markdown files, and how the injection system works under the hood.
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Tweag by Modus Create @tweag.io · 30/06/2026
Christian Georgii presents tricorder at the Haskell Foundation's "Haskell and AI" workshop. A new DX tool providing simple, fast and focused feedback for building Haskell programs. He'll show you how it works and what can be tweaked to adapt it to your workflows. 🎥 youtu.be/vDmyl0ZJRF8?...
youtu.be
Haskell and AI Workshop
Welcome to the Haskell Foundation online workshop on AI and Haskell! 11:30 Alfredo Di Napoli: Consulting for clients who use AI: a tale of a few hats 12:00 Gautier Di Folco: LLM as a SDLC…
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Arnaud Spiwack @aspiwack.bsky.social · 19/06/2026
I wrote about my sheaves project in prose form. Code, even small as that project, doesn't give you a lot of navigation keys. So I wanted to make something a bit more sequential to help get the important points across. Let me know if it helps.
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Tweag by Modus Create @tweag.io · 18/06/2026
In his latest blog post, @aspiwack.bsky.social shows how, despite textbook definitions suggesting the contrary, sheaves (from category theory) can be implemented in ordinary functional programming languages. www.tweag.io/blog/2026-06...
tweag.io
Sheaves in Haskell
Here is how you can implement sheaves in Haskell
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Tweag by Modus Create @tweag.io · 11/06/2026
In his latest blog post, Xavier Góngora dove into a Haskell library and used Liquid Haskell to statically check invariants that were previously only implicit. His verdict on the tooling today? "No blood, sweat and tears; just ripples, but encouraging ones at that." www.tweag.io/blog/2026-06...
tweag.io
Writing static checks to an unsuspecting library with Liquid Haskell
A self-contained example showcasing formal verification using Liquid Haskell
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Tweag by Modus Create @tweag.io · 05/06/2026
Announcing tricorder, an incremental build tool for Haskell: multi-component auto-discovery, a background build daemon and a TUI dashboard. Great to pair with LLM agents: it has a context-friendly CLI and includes a skill for tight feedback loops. tinyurl.com/dmpc8mbk
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Tweag by Modus Create @tweag.io · 04/06/2026
Introducing Scrawls 🦀 A #Rust library to read, write and verify SCLS files (CIP-0165): canonical #Cardano ledger-state snapshots with Blake2b-224 Merkle-tree integrity. Streaming, lazy and interoperable with the Haskell reference. 📦 crates.io/crates/carda...
crates.io
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Tweag by Modus Create @tweag.io · 29/05/2026
cooked-validators v9.0.0 is out! • Revamped effect system (Polysemy) • Refined balancing mechanism • Extended temporal logic DSL github.com/tweag/cooked...
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Manuel Chakravarty @tacticalgrace.justtesting.org · 28/05/2026
Check out the new blog!
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Tweag by Modus Create @tweag.io · 28/05/2026
build //newsletter issue 31 just dropped From remote caching tricks to running Claude prompts as Bazel actions, plus how to stop external resources breaking your builds .. there's something for every build nerd in this issue. BazelCon '26 in Amsterdam, who's going? build.news
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Tweag by Modus Create @tweag.io · 20/05/2026
Genealogos v1.1.0 is out! 👀 This release adds CycloneDX 1.5 support, updated dependencies, and fixes for `nix run`. Full details: github.com/tweag/geneal...
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Tweag by Modus Create @tweag.io · 19/05/2026
New release: linear-base v0.8.0 github.com/tweag/linear... . With some love shown to the resource-aware IO monad from contributor @dfacastro.bsky.social in support of their fascinating linear-locks library hackage.haskell.org/package/line...
github.com
Release v0.8.0 · tweag/linear-base
Full Changelog Headline changes Add MonadIO instances for StateT and ReaderT #506 (dcastro) Coerce System.IO and Linear.IO into RIO #505 (dcastro)
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Mike Sperber @sperbsen.bsky.social · 17/05/2026
FLOPS 2026, the 18th International Symposium on Functional Programming is less than 2 weeks away. The proceedings are available now in LNCS! link.springer.com/book/10.1007...
link.springer.com
Functional and Logic Programming
The FLOPS 2026 proceedings on all aspects of the design, semantics, theory, applications, implementations, and teaching of declarative programming.
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Haskell programming language @haskell.org · 14/05/2026
"linear-locks: locking primitives free of deadlocks" If you encounter STM's limitations when it comes to lock-free synchronisation, then Linear Haskell-backed locks maybe the solution you want! discourse.haskell.org/t/ann-linear... #Haskell
discourse.haskell.org
[ANN] linear-locks: locking primitives free of deadlocks
linear-locks provides locking primitives that are statically guaranteed not to lead to deadlocks. It achieves this by breaking one of the Coffman conditions for deadlocks: the “circular wait” conditi...
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Haskell programming language @haskell.org · 05/05/2026
The Haskell Paris Spring Meetup will happen on the 27h of May at ENS Ulm. See the announcement here: discourse.haskell.org/t/haskell-pa... Register here: www.meetup.com/fr-FR/haskel...
discourse.haskell.org
Haskell Paris Meetup announcements
The Paris Haskell meetup is back for Spring, in partnership with HackENS, ENS Ulm’s hackerspace. This will be the occasion to see each other, talk about the new things happening in the ecosystem, and...
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Haskell programming language @haskell.org · 08/05/2026
You can take a look at their engineering blog: exploring-better-ways.bellroy.com/teams/techno...
exploring-better-ways.bellroy.com
Blog posts from the Technology Team
Technology
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Haskell programming language @haskell.org · 08/05/2026
The Lambda Nantes Meetup will happen on the 21st of May, with speakers @clementd.wtf and @etorreborre.blog as speakers discourse.haskell.org/t/lambda-nan...
discourse.haskell.org
Lambda Nantes Meetup - 21 May
Hello, The Lambda Nantes Meetup is back in May, the 21st, with not one but TWO talks: Clément Delafargue (@clementd.wtf) will demonstrate that everything boils down to traverse Eric Torreborre (@et...
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Haskell programming language @haskell.org · 08/05/2026
The Tokyo Haskell Meetup will happen on the 19th of May with speakers Luite Stegeman and Farhad Mehta Discourse: discourse.haskell.org/t/haskell-me... Meetup: www.meetup.com/tokyo-haskel...
discourse.haskell.org
Haskell Meetup in Tokyo - 19 May
We have two talks (in English) lined up for the Tokyo Haskell meetup on 19 May: The Missing Haskell DevTools Luite Stegeman Hoogle for the Hungry Masses! Farhad D. Mehta Please use the Meetup lin...
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TNG Technology Consulting GmbH @tngtech.com · 30/04/2026
Attention all #Haskell fans: #MuniHac, our annual Haskell gathering, will take place in Munich from October 9th to 11th. Join us for a weekend of coding, learning, and hanging out with the international Haskell community. More information and the registration: munihac.de/2026.html
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Haskell programming language @haskell.org · 29/04/2026
Congratulations Clash!
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Haskell Interlude @haskellinterlude.bsky.social · 27/04/2026
We sat down with Torsten Grust who is a professor of DB systems at the University of Tübingen. We talked about the best way to program databases, how to bridge the gap between regular programming languages and databases, and compiling just about everything to SQL. haskell.foundation/podcast/81/
haskell.foundation
Torsten Grust
Mike and Andres sat down with Torsten Grust, who is a professor of DB systems at the University of Tübingen. Even though Torsten loves SQL, he's used functional programming and Haskell to inform his w...
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Elf M. Sternberg @elfsternberg.bsky.social · 24/04/2026
A successful experiment in giving Haskell Rust-like affine discipline! Eventually, you might be able to run Haskell with completely predictable memory behavior in both scope and timing! This is absolutely wonderful: discourse.haskell.org/t/pure-borro...
discourse.haskell.org
Pure Borrow: Linear Haskell Meets Rust-Style Borrowing
TL;DR You can now use Rust-style mutable and shared borrows in Linear Haskell, within ST-like linear monad, BO, with pure, type-safe, and leak-freedom support of mutation and concurrency! It comes wit...
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Haskell programming language @haskell.org · 23/04/2026
Pure Borrow: Linear Haskell Meets Rust-Style Borrowing discourse.haskell.org/t/pure-borro...
discourse.haskell.org
Pure Borrow: Linear Haskell Meets Rust-Style Borrowing
TL;DR You can now use Rust-style mutable and shared borrows in Linear Haskell, within ST-like linear monad, BO, with pure, type-safe, and leak-freedom support of mutation and concurrency! It comes wit...
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Arnaud Spiwack @aspiwack.bsky.social · 22/04/2026
A quick thread-of-thread of my observation on my small sheaves-in-Haskell project from the other week.
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Andres Löh @kosmikus.bsky.social · 21/04/2026
After a somewhat longer break, we're finally back with a new #Haskell #Unfolder episode. Tomorrow, 2026-04-22, at 18:30 UTC, Edsko and I will talk about selective applicative functors. www.youtube.com/watch?v=Yt2E...
youtube.com
Not quite monads (Haskell Unfolder #54)
YouTube video by Well-Typed
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Rust Language @rust-lang.org · 17/04/2026
Curious what's new in Rust 1.95.0? Check out this video of Cameron, Pete, and Tyler discussing the new release: www.youtube.com/watch?v=NZlm...
youtube.com
Rust Release Changelog - 1.95.0
YouTube video by Rust Programming Language
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Tweag by Modus Create @tweag.io · 16/04/2026
When your README's a monolith, doc it like it's hot! xophmeister.hachyderm.io.ap.brid.gy walks through three projects where documentation earned its place, featuring a crew of unlikely collaborators 🎤 www.tweag.io/blog/2026-04...
tweag.io
𝕯𝖔𝖈 𝖎𝖙 𝖑𝖎𝖐𝖊 𝖎𝖙'𝖘 𝖍𝖔𝖙
When the code's in the crib, ma...
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OCaml @ocaml.org · 15/04/2026
dlvr.it
OCaml-LSP 1.26.0
This new release of OCaml-LSP brings several new features and improvements, including new custom requests, support for range formatting, and enhanced hover capabilities.
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Haskell Interlude @haskellinterlude.bsky.social · 13/04/2026
In this episode from POPL 2026, we talk about: undergrad funding and participation, the behind the scenes of AV, choreographic programming, quantum languages, conference catering, and the joy of theory. haskell.foundation/podcast/80
haskell.foundation
POPL 2026 - Part 1
This is the first part of a miniseries on this year's Symposium on Principles of Programming Languages, a.k.a. POPL 2026, hosted by Jessica Foster.
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Software Heritage @softwareheritage.org · 13/04/2026
Software Heritage is building the world's largest source code archive🌍💻 We’re #hiring for key roles in France: • Backend Engineer • DevOps Engineer • Internal Apps Manager Join our mission! ➡️ www.softwareheritage.org/jobs
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Software Heritage @softwareheritage.org · 09/04/2026
The Source Code Exhibition is at the Sorbonne until April 25. The collection includes the RSA T-shirt, ELIZA & more in celebration of the first decade of Software Heritage. Details: shorturl.at/aocnu Visit the exhibit online: shorturl.at/keffF #SWH10
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Tweag by Modus Create @tweag.io · 02/04/2026
We are pleased to partner with the Haskell Foundation to promote the development of Haskell. We're offering Development Partnerships in four areas -- build and scale, polyglot integrations, distributed systems, and GHC contributions. haskell.foundation/partnerships...
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Tweag by Modus Create @tweag.io · 02/04/2026
Bazel builds often depend on GitHub, PyPI, and other external services in subtle ways, which means third‑party incidents can break an otherwise healthy CI. In his latest post, Alexey shares practical techniques to make external dependencies explicit and resilient. www.tweag.io/blog/2026-04...
tweag.io
Accessing external resources reliably with Bazel
Learn how to minimize risks when having third-party dependencies.
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Anil Madhavapeddy @anil.recoil.org · 01/04/2026
This is such an ingenious Apr 1st PR from Stephen Dolan I feel like it's the exact opposite of AI slop github.com/ocaml/ocaml/...
github.com
C++ support by stedolan · Pull Request #14701 · ocaml/ocaml
This patch adds a new C++ backend to ocamlc, improving on the unincremented C currently in use by the runtime and FFI. As an example, here's a simple program that computes the prime numbers up ...
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Haskell programming language @haskell.org · 30/03/2026
With "Haskellers from the trenches", the #Haskell blog lets experienced engineers talk about their subjects of expertise, best practices, and production tales. We start with @iankduncan.com's "A Couple Million Lines of Haskell: Production Engineering at Mercury" blog.haskell.org/a-couple-mil...
blog.haskell.org
A Couple Million Lines of Haskell: Production Engineering at Mercury | The Haskell Programming Language's blog
What it takes to run 2 million lines of Haskell in production at a fintech company serving 300,000 businesses.
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Arnaud Spiwack @aspiwack.bsky.social · 18/03/2026
I watched this video recently www.youtube.com/watch?v=N_-0... and I found it strangely compelling. I'm quite impressed at the immediacy of the visual feedback. If I get into teaching again, I'll consider Pico8 as a platform for beginner-level classes.
youtube.com
How Pokémon Fit All of Kanto onto the Game Boy
In this video we do a deep-dive into Pokémon Gen 1 trying to understand how it stores the map data of the Kanto region. Based on this knowledge we re-create Kanto on the Fantasy Console Pico-8 with…
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Tweag by Modus Create @tweag.io · 18/03/2026
Graphviz is definitely a great visualisation tool. Thanks for the library!
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Functional Architecture @funarch.bsky.social · 11/03/2026
Hello everyone, I am happy to announce that the Functional Architecture workshop has been accepted to this years ICFP! The Call for Papers for FUNARCH2026 is open - **deadline is June 1st**! See (icfp26.sigplan.org/home/funarch...) for more information. See you in Indianapolis!
icfp26.sigplan.org
FUNARCH 2026 - ICFP 2026
The Fourth ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large Say the word “combinator” to an average software practitioner and watch as you’re met with confusion. The function...
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NixOS Foundation @nixos.org · 06/03/2026
At the recent #Nix #Bern #meetup Michael Stapelberg, the inventor and maintainer of the i3 window manager, talked about why he switched to Nix. Michael is a former Debian Linux Developer, and creator of the Go appliance platform gokrazy. He tried NixOS from time to time, finally went all in in 2025
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Rust Language @rust-lang.org · 05/03/2026
Rust 1.94.0 has been released! 🌈 🦀✨ A few highlights are array_windows() and element_offset() on slices, Peekable::next_if_map(), LazyCell::get and friends, and the new `include` key in config.toml to include other toml files! Check out the blog post for details: blog.rust-lang.org/2026/03/05/R...
blog.rust-lang.org
Announcing Rust 1.94.0 | Rust Blog
Empowering everyone to build reliable and efficient software.
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