We open-sourced lean4-markdown, a typed Lean 4 library for building Markdown documents programmatically. The idea is straightforward: if you're generating verification reports or audit traces in Lean 4, you want the document structure checked by the same type system as the rest of your code. Ill-formed Markdown becomes a type error rather than a runtime surprise.
This is part of a small ecosystem we're building around Lean 4 as a general-purpose platform, alongside lean4-flow and lean4-json-schema. Happy to answer questions about design tradeoffs.
We wrote about something we keep thinking about: the gap between code that runs and code that's provably correct.
The post walks through a simple Java banking app with three bugs that compilation won't catch, tests are unlikely to catch, and an LLM reviewing the code would almost certainly miss. The most interesting one is structural: LLMs reason within a context window, but the most dangerous bugs are global properties that cross component boundaries. The preservation of money in a transfer isn't a property of withdraw() or deposit() in isolation.
Curious whether others have run into this class of problem in production.
We’ve been working on a software verification platform designed for AI-generated code. As code assistants accelerate development, verification becomes the bottleneck.
In this post, we outline the core principles we’re using to design a trustworthy verification system:
• Explicitly model semantics when possible
• Make approximations and assumptions visible
• Avoid confident false positives and false negatives
• Surface uncertainty instead of hiding it
Our main idea is that trustworthiness isn’t about absolute certainty. It’s about being explicit about assumptions and limitations so engineers can make informed decisions.
Would love feedback from people working on formal methods, static analysis, or AI-assisted development.
Author here . This isn’t meant as advice or a productivity framework. It’s just a personal reflection on how becoming a parent changed the constraints around my time while building a startup.
Writing it after talking with a founder friend who just had a baby and felt he was failing at both work and parenting. Sharing in case it resonates with others in a similar situation. Happy to answer questions or clarify anything.
I’ve been building startups for years and became a parent along the way. For a long time, I thought having kids would hurt my productivity. What actually happened is that it forced me to take time seriously.
This isn’t a guide or advice. It’s just my personal experience on how parenting changed how I prioritize, say no, use my calendar, and think about work. Writing it down after a conversation with a founder friend who just became a parent.
Sharing in case it’s useful to someone in a similar situation.
This is the story of how I turned my passion for discovering records into onerecord.club, Spain’s first indie vinyl subscription service.
In the article, I share the steps I took to transform a hobby into a tangible product: finding the right idea, teaming up with the right people, and navigating the challenges of launching something new.
If you're curious about how to turn what you love into something others can enjoy too, check it out! I'd love to hear your take on turning hobbies into products.
I recently took a step back from my career to go on a sabbatical, and it’s been a surprising journey—both liberating and challenging in ways I didn’t expect.
In my latest blog post, I share what I’ve discovered about how time, priorities, and creativity shift when you’re no longer tied to the grind. This might resonate with you if you’ve ever thought about taking a sabbatical (or just wondered what it’s like).
I would love to hear your thoughts or experiences if you’ve been through something similar!
I just published an article on my blog about the emotional rollercoaster I faced after selling my company.
The impostor syndrome hit hard as I transitioned from being a founder to navigating a large corporate environment. I dive into the insecurities, the struggle with accountability, and how to find a purpose in this new setting.
In my latest blog post, I highlight the value of kindness over intelligence in the workplace. I talk about how being kind—through listening, respecting others, showing empathy, and focusing on solutions—can significantly enhance team dynamics and productivity. While being smart is important, I believe that kindness leaves a lasting impact and creates a more positive and effective work environment.
I recently wrote about a unique team-building activity where my colleagues and I cooked and shared a meal together. It turned out to be a heartfelt and meaningful way to connect. If you're interested in fresh team-building ideas, you might enjoy this:
I find managing uncertainty both challenging and rewarding. It involves staying flexible, trusting instincts, and using creativity. Leading a team is like running a small business within a larger organization, offering chances for innovation and growth. Embracing uncertainty builds resilience and adaptability, leading to success in projects and team dynamics.
Organizing a tech conference is challenging but rewarding.
The Lambda World team shared insights from their experience organizing the annual Functional Programming conference in Cádiz.
Key Takeaways:
Planning Essentials:
Define your target audience and tailor the event to their needs.
Build a diverse, cohesive team with a shared vision.
Establish a strong ideology and incorporate local culture.
Budgeting Basics:
Calculate expenses (food, venue, speaker costs, A/V, design).
Set ticket prices considering sponsorships and attendee numbers.
Sponsor Management:
Understand company budget cycles and approach sponsors early.
Research similar conferences for potential sponsors.
Design appealing sponsor perks and maintain post-event communication.
Speaker Coordination:
Conduct background checks to ensure alignment with your conference’s values.
Include clear deadlines in communications and ensure timely responses.
Cover speaker expenses and offer travel booking options.
Attendee Engagement:
Foster open communication via emails, newsletters, and chat platforms.
Use tools like Eventbrite, MailChimp, and Typeform for ticketing and feedback.
General Advice:
Delegate tasks effectively and prepare for last-minute issues.
Stay humble, be nice, and handle conflicts with care.
Pay attention to details to give the event a unique identity.
Following these strategies, the Lambda World team successfully organized a meaningful and enjoyable conference supporting the local economy and community.