Scala Days 2025: My Experience as a Volunteer

I was a volunteer at the 2025 Scala days, in Lausanne.

It was pretty wholesome to meet in person some of the famous Scala contributors, but also its creators, in the birth place of Scala: EPFL. For me, this was also the opportunity to meet my GSoC mentors in person, and get my work on LLM4S presented in their talk :)).
Huge thanks to them for the moment of spotlight. ✨

Functional stream processing workshop

I was lucky enough to attend Zainab Ali's workshop on stream processing with fs2. She shared a really nice mental model for how to think about streams, using diagrams called aquascapes to illustrate the behavior of fs2 operators. You can check them out here. Once you internalize how aquascapes work, understanding how any function transforms a stream becomes way easier.

Conference talks

From composing music through FP to learning about compiler engineering in Scala, each talk was packed with insights in areas where Scala thrives. It was also inspiring to hear the journeys of so many Scala enthusiasts.

A recurring theme across talks was how Scala, with its focus on immutability and a strong type system, helps us write programs that mirror the real world more faithfully. Instead of working with changeable machine state, we're encoding immutable truths and shaping them through types that capture meaning, enabling our code to model reality directly.

That made me think of Lavoisier's principle of conservation of mass: "Nothing is lost, nothing is created, everything is transformed".
It resonates with immutability in Scala, where everything is transformed, Types ensure only valid transformations, and Purity makes those transformations predictable and explicit.

My favorite talk was the panel with Martin Odersky (creator of Scala), Dimi Racordon, Evan Czaplicki, Ralf Jung and Li Haoyi (whose libraries I've relied on many times) where they discussed functional programming and the real world.
Some hot takes came up — like whether Rust should be considered a functional language, or the limitations of Scala itself.

Li Haoyi said one thing I found interesting. He pointed out (as I understood it) that Scala hasn't spread in production as widely as some other languages because of its limitations. But at the same time, those limitations leave plenty of space for the language to evolve, and recognizing them is the first step toward making Scala stronger.

Overall, volunteering was so worth it! It was amazing to meet and connect with fellow volunteers, my amazing mentors and of course the organizing team :))

Fun Fact: The Scala Stairs

I learned about the Scala stairs probably in my second year at EPFL, but it wasn’t until I had to shuttle visitors there as a volunteer (felt like a tour guide at some point) that I realised how big of a deal they actually were. I took these stairs so many times (ngl took the elevator more often..) without ever realising it's a sort of temple for some.

So after 4 years at EPFL, I decided maybe it's time I also take a pic here :))