Thanks to all our speakers and attendees for a fantastic #PLSS 2025 workshop!
From formal specs to pragmatic design, and from legacy lessons to new languages, we saw the many ways programming languages evolve, and the people who shape them. Until next time!

Closing out the workshop, Michael Sperber from Active Group GmbH asked: "Do Programming Languages Fulfill Requirements? Should They?". Michael reflected on Scheme standardization, the balance between elegant theory and practical needs, and designing languages for long-term evolution.

Jarkko Järvi from University of Turku ‪@utu.fi‬ talked on " #C++ Standardization: Reflections and Lessons Learned". Jaakko shared insights into the technical challenges and social dynamics, and the long road that led to lambdas, concepts, and other language features.

Jaehyun Lee from KAIST presented "P4-SpecTec: Mechanized Language Definition for P4". Jaehyun showed how to bring consistency to the evolving #P4 language via a mechanized spec model, building language tools from a single formal source.
p4.org/wp-content/u...

Karta Kooner from Dyalog @dyalog.bsky.social presented "APL Standards", highlighting how gaps and ambiguities in the #APL specification affect real-world interpreter development. Karta's talk reviewed how Dyalog APL aligns with the standard and where it diverges.
www.dyalog.com/blog/2025/07...

Michael Ficarra @michael.ficarra.me from F5 presented "The Software Supporting the JavaScript Language Specification". Michael gave an in-depth tour of the tools and web-based infrastructure that power #ECMA-262, turning the #JavaScript spec into a collaborative document.
262.ecma-international.org

Marat Akhin from JetBrains ‪@jetbrains.com presented "Just-in-time Specification: Evolving Kotlin One Feature at a Time". Marat shared how #Kotlin evolves pragmatically, driven by user needs, validated by real code, and specified just enough to guide the design.
github.com/Kotlin/KEEP

Dimi Racordon from EPFL presented "Designing Hylo, a programming language for safe systems programming", built on mutable value semantics.
Dimi also shared lessons from building and sustaining a new language project in academia and open source.
www.hylo-lang.org

Jihyeok Park from Korea University talked about "Trusted JavaScript Language Environments with ESMeta". Jihyeok introduced ESMeta, a framework for formalizing #JavaScript semantics and building verified tools, advancing the reliability and trustworthiness of the language.
dl.acm.org/doi/pdf/10.1...

Adám Brudzewsky @abrudz.bsky.social from Dyalog @dyalog.bsky.social presented "APL Array Notation". Adám explored how to extend #APL with a clear, consistent syntax for #array construction, bridging terse expressiveness with readable, modern notation.
apl-germany.de/wp-content/u...

The workshop was kicked off by the keynote given by Andreas Rossberg, the editor of #WebAssembly specification.
Andreas presented "Engineering a Formal Language Specification", introducing Spectec, a DSL that generates the full #Wasm spec from a single formal source.
webassembly.org/news/2025-03...