Gradually Typing Ruby with RBS / Decorating Gems

Wed, 12 Apr 2023 19:00 - 21:30 JST

Impact Hub Tokyo

東京都目黒区目黒2-11-3 印刷工場1階


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¥1,500 prepaid
A light meal will be provided


COVID-19 Policy

Having an event is not without risks, but we need your help to keep them minimal. If you are feeling unwell, please do not attend the event. Also, you're required to wear a mask at the event, with the exception of while you're eating.


19:00 〜 19:15 Doors open

Drop by and catch up with your fellow Rubyists. Please note, the doors will close at 19:30, so please arrive before then.

19:15 〜 19:30 Catering served

Thanks to our catering sponsor, we're going to serve a freshly cooked meal. On the menu is

  • Mixed vegetable salad with two kinds of dressing
  • Vegan fries (jambalaya style)
  • Cabbage and citrus rosemary marinade
  • Mushroom potato salad
  • Empanadas (meat pie)
  • Spanakopita (vegetable pie)
  • Dessert (fruits, etc.)

19:30 〜 20:00 Gradually Typing Ruby with RBS - Nemo Oudeis

When I joined Moneytree I had to learn an organically-grown, 10-year-old codebase. I had tests, I had a language server & IDE to help me understand the code. But it just wasn’t enough, I longed for the help of static types that I’ve grown to love languages like Kotlin and TypeScript.

In this talk I’ll share how I brought static typing with RBS to a mature ruby code base. From “hello world 🎉” to “hello real world 🤯” (aka or “why doesn’t this work?! 👿”).

After attending this talk you will know if RBS is a good fit for you and know how to start using it.


Hi, I’m Nemo 👋, a recent Rubyist.
I enjoy working in small & independent product teams.
I work as a senior engineer at Moneytree.
I also enjoy gardening 🪴

20:00 〜 20:30 Decorating Gems - Paulo D'Alberti

Gems are an intrinsic part of Ruby development, but sometimes we would like to modify a small part of the code to better match our needs. Decoration is one of the strategies that can be employed to achieve this goal, and this presentation will show how to use it, as well as discuss pros and cons.


Ruby on Rails developer and contributor to gems such as the open source eCommerce platform Solidius, Faker, and Rspec. Public speaker, former startup founder, and tech advisor. Searching for my next opportunity, so please don't hesitate to get in touch!

20:30 〜 21:30 Open Networking

Discuss the presentations or anything else Ruby related with the other attendees.

Catering Sponsor

TokyoDev helps international developers start and grow their career in Japan. We curate a list of developer jobs in Japan that don't require Japanese, write articles about being a developer here (including our recently published article on working as a female software developer in Japan), and have a discord server to discuss developer life here.

Drink and Venue Sponsor

Le Wagon Tokyo is a coding school for startups, creative people and tech entrepreneurs. Our 9-week full-time or 24-week part-time Coding Bootcamps are designed for complete beginners or "half-beginners" who really want to dive into programming and, above all, change their mindset. Learn to think like a developer, consider issues with new insight, and become more autonomous thanks to these newly acquired abilities.

Code of Conduct

Tokyo Rubyist Meetup is a safe and inclusive event. By attending, you agree to our code of conduct.

We're looking for speakers!

Tokyo Rubyist Meetup would love to have you give a talk at a future event. Talks can be anything related to Ruby, and can target anyone from a beginner to an expert. We're happy to help you plan your presentation, so if you have any interest, please get in contact with us, and let us know what you're interested in speaking about.

About this community

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup (trbmeetup) is an event that seeks to help bridge the Japan and international ruby and ruby on rails community. It will hold regular meetings where Japanese Rubyists can commun...

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