Open Source

​Informal meetup for people interested in OpenClaw and AI agents. We share what works/what doesn't and what we’re currently trying. Feel free to bring your laptop and half-working setup. We're all here to learn how to ride the tiger \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- ​Events usually unfold in two parts: 1st part - People showcase projects, tools, setups and discuss learnings 2nd part - Open discussion/networking

We are back in the c-base! Do you already run NixOS and want to talk to other people or want an introductory session with some NixOS users. Just bring your machine! Usually there are no topics, we just sit in front of our computers, talk about stuff, debug some problems or review some PRs on nixpkgs. There are drinks usually available from the c-base bar. If you can't find us. just ask around or ask in irc (#krebs on hackint)

The next **Berlin C++ Meetup** hosted by think-cell takes place on **Tuesday, May 26**. Join us for an evening with the Berlin C++ community! This meetup is a chance to step away from your day to day work, meet other developers, exchange ideas, and have real conversations about modern C++ in a relaxed setting. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- ## **Talk** ### **Contract assertions on virtual functions** *Timur Doumler – Citadel Securities* Contracts assertions were introduced in C++26, but they cannot be applied to virtual functions. To close this gap, we first need to answer the question: how should contracts assertions behave in the presence of inheritance and runtime polymorphism? In this talk, Timur explores why this problem is harder than it looks. He reviews existing approaches from other languages, such as Eiffel, D, and Ada, highlights why they don’t fully translate to C++, and outlines the key design challenges involved. He then presents a concrete proposal for how contract assertions on virtual functions could work in C++, balancing correctness, safety, and usability. Along the way, the talk touches on good API design, the true meaning of the Liskov substitution principle, and how to reason about program correctness. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- 📅 **Date & Time:** Tuesday, May 26, 2026 – 18:30–21:30 📍 **Location:** Le Wagon Coding Bootcamp, Rudi-Dutschke-Straße 26, 10969 Berlin 5th floor 🕒 **Agenda** 18:30 – Doors open 19:00 – Talk + Q&A 20:40 – Pizza, Drinks and Networking \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- **RSVP now to save your seat!**

Need a mid-week pick-me-up? Join us for **Sip Happens!** this week at Electric Social, where good beer and great games come together for a fun and fantastic social night! Whether you're a board game pro or just looking for a chill night out and a fun way to socialize, there's something for everyone. Grab a beer (or cider, or wine, or even a tea!), **pick (or bring) a game,** and meet some new friends as we roll dice, play cards, and laugh the night away. From classics like Catan and Scrabble to party favorites like Cards Against Humanity, we’ve got it all. Coming straight from work? No problem...the kitchen serves awesome food as well! 😉 So, round up your mates or come solo—either way, you’ll leave with new friends and fun memories. Cheers to making midweek nights something to look forward to! 🍺🎉 We always have several organisers there (male and female), so come say hello to us! We care to make sure that everyones enjoys themselves and we have **no tolerance for bad behaviour or creepiness.** **Follow us on Insta:** @siphappens.berlin **Join us on Telegram:** t.me/siphappens_berlin **👉 Other important notes:** \- 🍸 The locations we visit are bars and clubs\, they are businesses and we are able to keep these events free ONLY if people buy drinks\. Please respect the locations and the event by making purchases \- 🦹‍♂️ Remember to keep an eye on your belongings and prioritize your own well\-being\. We are not responsible for any lost items or personal issues\. \- 📷 By attending our events\, you consent to being photographed or filmed\. Photos and videos taken during the events may be shared on our social media\. If you do not wish to appear in the photos or if you appear in a photo that we post that you would like removed\, please send us a private message as soon as possible on Instagram \(@siphappens\.berlin\)

BHNT #112: the fifth BHNT in 2026. The title is inspired by the issues around Bambulab (Boo). Your hacks do not have to be connected to the title (bonus points if they do though) Please RSVP and bring your hacks! There are 8 dynamically allocated Slots that consist of 5min presentation + 5min conversation with the audience. To refresh your memories or get familiar with the concept - see some old hacks here: [https://bhnt.c-base.org](https://bhnt.c-base.org/) Hope to see you - looking forward! [RSVP here](https://platform.openmeet.net/events/bhnt-112-bamboo-hacks-8zv0v)

**🎶 American Church Choir in Berlin – Come Sing & Connect** Looking to meet new people in Berlin? Love music—or at least enjoy singing in the shower? You’re warmly invited to join the **American Church Choir** for an evening of community, creativity, and connection. **No professional experience needed.** If you can carry a tune (or even if you're not sure), you’re welcome. Our group is relaxed, supportive, and full of people who simply love singing together. **What to expect:** * Easygoing choir rehearsal * A mix of styles—nothing too formal * Friendly people from around the world * Zero pressure, lots of encouragement And afterward? **We’ll open a bottle of wine (or two) and just hang out.** It’s a great way to meet others, make friends, and unwind mid-week. **📍 Where:** American Church in Berlin (Dennewitzplatz) **🕒 When:** Tuesdays at 7pm (19:00) **🎵 Who can join:** Anyone who likes music, community, and good company Come as you are. Bring a friend if you’d like. We’d love to meet you! 🍷🎶

## Learn Go and NixOS deployments with large language models Hello, 世界! When used sensibly, language models can be tutors, too. For meetup #60 on Tuesday [May 26, 2026 19:00 CET](https://www.meetup.com/leipzig-golang/events/312537727) we are really happy to have [Maxime](https://www.linkedin.com/in/plumps/) dive into Nix/NixOS with the help of language models. Nix is a functional package manager and its immutable traits enable robust, reproducable deployments of Go (and other) projects. The high level goals of Nix/NixOS are similar to other immutable Linux distributions, like [Silverblue](https://fedoraproject.org/silverblue/) or [Bazzite](https://bazzite.gg/). Becoming familiar with the Nix configuration language can be a challenge, but one that a well instructed tutor may help with. > Artificial intelligence techniques are increasingly used in education to enable personalized learning and intelligent tutoring [LLM Agents for Education: Advances and Applications](https://aclanthology.org/anthology-files/anthology-files/pdf/findings/2025.findings-emnlp.743.pdf) (11/2025) Why reproducible and immutable deployments play a role? [Justin Garrison](https://justingarrison.com/blog/state-of-immutable-linux/) says: > It’s 2026, if you’re not using something immutable (or at least reproducable) you’re doing more maintenance work than you should. [blog post recapping talk from [Southern California Linux Expo 23x](https://www.socallinuxexpo.org/scale/23x)], 03/2026, PASADENA, CA ### Schedule * 18:45 Doors open * 19:00 Welcome * 19:10 Dive into Nix/NixOS with LLMs * 19:50 Open discussion We’ll meet: * in person at [Basislager Leipzig](https://basislager.co), at [Peterssteinweg 14, 04107 Leipzig](https://maps.app.goo.gl/1fMkeDSPZ7Aauszh8) ([OSM](https://www.openstreetmap.org/node/3504864558)) * and online via [https://meet.google.com/drk-bptj-xss](https://meet.google.com/drk-bptj-xss) Join us to discuss robust Go deployments, language models as learning tools and more!

Welcome to the PyData Berlin May meetup! We would like to welcome you all starting from 18:00. There will be food and drinks. The talks begin around 18.30 and the doors will close at 18:45. **Make sure to arrive on time!** Please provide your first and last name for the registration because this is required for the venue's entry policy. If you cannot attend, please cancel your spot so others are able to join as the space is limited. **Host**: **GetYourGuide** is excited to welcome you to this month's version of PyData. \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* The Lineup for the evening **Talk 1: Text2SQL in the Wild — Agentic Workflows & Semantic Models on Customer Data** **Abstract**: Translating a business user's natural language question into a reliable SQL query has huge value for business analysts, but doing it accurately at scale, on messy enterprise data, for complex queries, is incredibly difficult. This talk walks through a production Text2SQL system built on four pillars: semantic models built on customer data, RAG-based semantic search, an agentic verification and correction loop for building the SQL, and an evaluation framework for the entire process. Raw schema information is not enough for text2sql to work. Rather, thorough documentation including business metrics, synonyms, and qualified example queries, are required. We'll cover how to automate this documentation pipeline by mining query logs, generating descriptions with LLMs, and organizing everything into a knowledge graph and vector search index. From there, we'll dive into the agentic flow that takes a user question and iteratively generates, validates, and fixes SQL against a live database. The agentic framework analyses syntax errors and execution results to help it fix the SQL. Participants will leave with practical takeaways on RAG architecture for structured data, agentic retry patterns, and how to think about evaluation for Text2SQL systems in production. **Speaker**: Oren Matar **Bio**: Oren Matar is a principal data scientist and algorithms developer, with a background in social sciences and Bayesian methods. He specializes in NLP and time series forecasting, as well as agentic methods for data retrieval and processing. **Talk 2: Interpreting and Communicating Statistical Models** **Abstract**: Extracting actionable insights from complex statistical models remains a challenge, as raw coefficients are often uninterpretable due to nonlinearity, interactions, or hierarchical structures. This talk introduces a unified framework for model interpretation based on the principles of the Marginal Effects project ([https://marginaleffects.com/](https://marginaleffects.com/)). We move away from internal model parameters toward quantities of interest, such as marginal effects and adjusted predictions that translate statistical output into the "natural language" of the data. We will demonstrate these concepts in Python using the Bambi interpret module, showcasing a seamless workflow for interpreting Bayesian models built on PyMC. The audience will learn how to use the four primary interpretative pillars: Predictions, Comparisons, Slopes, and Marginal Means to compute average marginal effects and visualize conditional relationships. By the end of this session, you will be equipped to turn sophisticated GLMs and multi-level models into clear, rigorous narratives that are easily communicated to stakeholders. **Speaker**: Juan Orduz **Bio**: Juan is a Mathematician (Ph.D. Humboldt Universität zu Berlin) and Principal Data Scientist at PyMC Labs. He is interested in interdisciplinary applications of mathematical methods. In particular, time series analysis, Bayesian methods, and causal inference. **Lightning talks** There will be slots for 2-3 Lightning Talks (3-5 Minutes for each) between the two main talks. Kindly let us know if you would like to present something :) \*\*\* NumFOCUS **Code of Conduct** THE SHORT VERSION Be kind to others. Do not insult or put down others. Behave professionally. Remember that harassment and sexist, racist, or exclusionary jokes are not appropriate for NumFOCUS. All communication should be appropriate for a professional audience including people of many different backgrounds. Sexual language and imagery are not appropriate. NumFOCUS is dedicated to providing a harassment-free community for everyone, regardless of gender, sexual orientation, gender identity, and expression, disability, physical appearance, body size, race, or religion. We do not tolerate harassment of community members in any form. Thank you for helping make this a welcoming, friendly community for all. If you haven't yet, please read the detailed version here: https://numfocus.org/code-of-conduct \*\*\*

**Rust Berlin Talks** is back for another evening of talks, shared ideas, and networking. Join us to learn, share, ask, and connect. If you work with Rust professionally, use it in side projects, contribute to open source, or are simply curious to learn more, you are very welcome. **Agenda** * Doors open: 18:30 * Start: 19:00 * Talks * Open mic / lightning talks * Networking **Speakers** Egor Lebedev - Welcome and a short note from the RustRover team Wolf Vollprecht - Pixi - A cross-platform package manager written in Rust One more speaker - To be announced soon **Speaker Bios** Wolf Vollprecht is the founder and CEO of prefix.dev, where he builds open-source software supply chain infrastructure for the conda ecosystems. Core projects include Pixi (a cross-platform package manager written in Rust), rattler (crates to work with Conda packages), and rattler-build. With \~7 years in the conda ecosystem, including creating Mamba during his time at QuantStack, Wolf has a lot of experience in making package management fast, reproducible, and secure. **Open mic & future talks** We’ll reserve a few short slots for anyone who wants to share something with the group. This can be a quick idea, a project, or an experience. Slides are optional. If you’re interested in giving a longer talk at a future meetup, this is also a good opportunity to connect with the organizers. **Venue & access** Please arrive on time. We will have someone at the entrance to let people in between 18:30 and 19:15. After that, access becomes more difficult as the doors are locked and require manual opening. **Registration** The venue has limited capacity and events typically fill up with a waiting list. If you register and can no longer attend, even at short notice, please un-RSVP so someone else can take your spot. Looking forward to seeing you all!

Join us for an evening on the practical side of AI agents. We'll dig into context engineering and why relevance matters more than prompt tricks, then look at what it takes to run autonomous agents safely alongside humans. Food and drinks provided — stick around after for networking. ✍️ RSVP asap as capacity is limited so grab your spot asap! 📅 **Date and Time** Wednesday, May 27, 2026 from 18:00-20:45 📍 **Location** [EBCONT office, beyond Quartier Heidestrasse, 34, 10557 Berlin](https://maps.app.goo.gl/aQGPgteqhQ2yrmx96) 📝 **Agenda** 18:00 – Doors open, arrivals and check-in 18:20 – Welcome note by EBCONT 18:30 – **Agent Builder Hope is not a strategy — relevant context for data driven agents** by Anderson Queiroz — Elastic *What are agents and context engineering? And why we think the "center of gravity" for context engineering is much more about relevance and your data than only prompts and memory management.* 19:00 – Q&A & quick break 19:15 – **Adapting to AI in Security** by Jenny Pinheiro — Tines *Best practices for autonomous AI and human interaction in the context of workflows.* 19:45 – Pizza, drinks & networking \*\*\* Invite your friends and join us for an evening of learning and networking with fellow engineers and speakers! Thank you to **EBCONT** for hosting and to **Tines** for teaming up with us on this one!

**Build for Everyone — Accessibility for Mobile** Flutter Berlin is hosting a joint meetup with Kotlin User Group Berlin and CocoaHeads Berlin, focused on building accessible mobile apps. **Location:** Hedwig-Dohm-Haus, Berlin We’ll cover both strategy and hands-on implementation — from understanding platform differences (Android, iOS, cross-platform) to real-world accessibility pitfalls and live testing. With: **Important:** Registration is via Luma, not Meetup. Please register here: https://luma.com/xo7d3vb4

"No half-thruths, just naked minds” Welcome to the comedy show where you can see unfiltered comedians speak their thruth since almolst 5 years! Their topics can range from their last sexual encounter to why they hate chickens and how to win a fight with a chesse sandwich. So expect any kind of material from clean to the very dark. Each comedian will have between 5-10 minutes to make you laugh. The show is located in the cozy Agata Bar on Weichselstraße 55 in Neukölln - open for all of those who appreciate cozy nights and a fine selection of drinks and good mood. The space is limited, so the early bird catches the worm - get a reservation for your own good! Doors: 19:30 Show: 20:00 Get your free reservation now & pay what you want for the show! *Reservations are only kept until 20:15, so please arrive before that for assured seating.

**Bob on Tour – IBM Bob live erleben 💙** Wie fühlt sich ein agentischer Coding Assistant im echten Entwicklungsalltag an? Bei **Bob on Tour** kannst Du IBM Bob gemeinsam mit Expert:innen hands-on ausprobieren. In einem eintägigen, technisch fokussierten Format arbeitest Du an realistischen Coding-Aufgaben, von geführten Labs bis zur Anwendung auf eigene Use Cases. Dabei lernst Du, wie Bob Entwicklungsworkflows ergänzt, Codebasen verständlicher macht und mehrstufige Aufgaben unterstützt. **Das nimmst Du mit:** ✅ Sicherer Umgang mit den wichtigsten Bob-Funktionen ✅ Praktische Erfahrung mit agentischer Coding-Unterstützung ✅ Impulse für reale fachliche und technische Problemstellungen 👉 **[Jetzt anmelden und IBM Bob live erleben](https://luma.com/5g0x9318)**

Welcome to our cosy Godot Engine Community Meetup! This is not a structured meeting, but rather a friendly get-together. We will hang out, chat and maybe show some of our current projects! 🦜 Regardless if you are an artist, designer, programmer, beginner, hobbyist, professional or anything in between: join us for sharing knowledge, creating art together, coding together, joining game jams together and having fun! 🌼 This meetup will happen at [Saftladen Game Collective](https://saftladen.berlin), Normannenstraße 1-2, 10367 Berlin-Lichtenberg. 🌳 You can also join us on [our Discord Server](https://discord.gg/Sm3CgrqqQa). ☎️ Follow us on [Mastodon](https://mastodon.gamedev.place/@GodotUserGroupBerlin) for updates. 📢 Also check out [our website](https://godot.berlin). 🌐 Please be [excellent to each other](https://godotengine.org/code-of-conduct/)! 🕊️

Columbus Code & Coffee is an inclusive, informal co-working session. People of all skill levels attend, and we love it that way. Many people (optionally) bring projects to work on, and many other people (optionally) socialize the entire time. It's entirely up to you! **What to Expect at the Intro Circle** \~\~\~\~\~\~\~\~\~\~\~\~\~ Near the beginning of the event (1:30 pm), we do a standup: * Organizer announcements, updates, and logistics Round 1 - (7 secs max): * Your name * What you're working on * What you can help others with Round 2: * Community events you wanna plug. If none, that's cool too. Round 3: * Job opportunities you're hiring for OR announce that you are looking for one. If none, that's cool. After the introduction circle, everything is self-organized! Feel free to work alone, pair up, attend one of our workshops/presentations, or mingle!

Columbus Code & Coffee is an inclusive, informal co-working session. People of all skill levels attend, and we love it that way. Many people (optionally) bring projects to work on, and many other people (optionally) socialize the entire time. It's entirely up to you! **What to Expect at the Intro Circle** \~\~\~\~\~\~\~\~\~\~\~\~\~ Near the beginning of the event (1:30 pm), we do a standup: * Organizer announcements, updates, and logistics Round 1 - (7 secs max): * Your name * What you're working on * What you can help others with Round 2: * Community events you wanna plug. If none, that's cool too. Round 3: * Job opportunities you're hiring for OR announce that you are looking for one. If none, that's cool. After the introduction circle, everything is self-organized! Feel free to work alone, pair up, attend one of our workshops/presentations, or mingle!

Main Library, Meeting Room 2B Join us for a welcoming evening of reflection, gentle music, and meaningful conversation. We’ll begin with a short grounding moment, followed by a brief reading from spiritual or philosophical traditions, and an open reflection circle where participants can share (or simply listen). Libera Animae is an interfaith community focused on inner growth, creativity, and authentic connection. All backgrounds are welcome.

**Important time note:** Please plan on arriving between 5:30 and 6:00 as the elevators lock after 6 and you'll need to message us and we'll need to come get you. The building address is 4450 Bridge Park The entrance is 6620 Mooney St, Suite 400 You will need to scan your ID at the door to get a visitor badge. **Abstract** Like it or not, AI agents are now capable of turning a quickly written paragraph of requirements into a pull request that is ready to be integrated into real-world production applications and it's now our responsibility to make sure AI doesn't go rogue and take down prod - or corrupt our data by misunderstanding the requirements or our existing schemas. In this session we'll explore strategies to protect our codebases through unit and integration testing, documentation, and code review along with additional ways of providing context and guard rails to our AI agents as they carry out the work we've assigned them to do. By the time we're done, you'll have a firm grasp of the problem and understand some helpful options for protecting your codebase from vibe coding mishaps getting YOLOed into prod. **YouTube Link** https://youtube.com/live/BltmWMH1zG0?feature=share

Come out to Improving for our monthly iOS and Mac meetings. This Month's Presentation: Nothing yet. (You should volunteer). What is Cocoaheads (http://cocoaheads.org/)? CocoaHeads is a group devoted to discussion of Apple Computer's Cocoa Framework for programming on MacOS X and iOS (including the iPhone, iPad and Apple Watch). During monthly meetings, members present on their projects and offer tutorials on various programming topics. What is BuckeyeCocoa (http://buckeyecocoa.org/)? BuckeyeCocoa is a group of Objective-C/Swift developers/enthusiasts. We host monthly Cocoaheads and near-weekly NSCoder meetings in Columbus, Ohio. The meetings are free to attend. Presentations! Presenters welcome! We are always in need of people willing to present material. Any Swift and/or Objective-C related topic is welcome. Times can be 5 minutes (i.e. lightning talks) to a maximum of 2 hours. Interested? Contact info is on the BuckeyeCocoa website. To volunteer for a presentation contact us at @BuckeyeCocoa on Twitter. Follow us on Twitter! @BuckeyeCocoa (https://twitter.com/#!/Buckeyecocoa/) For more information: http://buckeyecocoa.org/

Bring your work or your hobby, hang out, and code with us. Follow @buckeyecocoa for more information.