Posts on defmarco.com

CoDaMo at Virtual Domain-Driven Design

Fri, 04 Sep 2026 00:00:00 +0000

Yesterday, my friend Martin Günther and I were given the opportunity to present your workshop “Collaborative Data Modeling: Discovering Domain Types Through Linguistic Cues” at Virtual Domain-driven design. We had a lot of fun and are thankful for all the helpful feedback from the participants.

Thanks so much to Andrea Magnorsky for the invitation and helping us set everything up and to everyone who joined, either in the session or live on YouTube. You can watch a recording of the whole workshop there as well.

Collaborative Data Modeling: DDD Europe und Virtual Domain-Driven Design

Mon, 17 Aug 2026 00:00:00 +0000

At the beginning of the year, I was introduced to Martin Günther. Whereas I come from a functional programming and data modeling background, Martin is an expert in Domain-Driven Design Collaborative Modeling. It quickly became clear that we see a lot of value in each others tools and techniques, while at the same time we realized that there are some holes in our “own” techniques: On the one hand, the DDD community seems to missing a systematic approach to date modeling that functional programming techniques bring to the table. On the other hand, while FP has the tools, the community is not always the most approachable and communication (and collaboration) with domain experts is not our strong suit, especially in groups of people with diverse (even non-technical) backgorunds.

Workshop: "FP in Typescript" at BOB 2026

Sat, 21 Mar 2026 00:00:00 +0000

My colleague at Active Group, Beat Hagenlocher prepared a workshop for BOB Konf 2026. Unfortunately, he got sick and I got to fill in spontaneously.

In the interactive tutorial, we watched and discussed the evolution of a SolidJS frontend app from state springled all over the place to a place where illegal states are unrepresentable, reducers make state transitions explicit and side effects are properly encapsulated. Using the approach we discuss, our core domain logic ends up completely independent of any SolidJS specifics.

Transducer Composition, Abstraction, Performance

Tue, 04 Nov 2025 00:00:00 +0000

I have just pushed a translation of my 2018 article “Transducer: Composition, Abstraction, Performance” on our Active group company blog (previously only available in German). In it, I dissect the how and why of Clojures transducers. Would love to hear your feedback! 🤩

You can read the full article on funktionale-programmierung.de (along with the original German version from 2018).

Bidirectional Data Transformations accepted to FUNARCH 2024 (ICFP)

Fri, 16 Aug 2024 00:00:00 +0000

Our paper Bidirectional Data Transformations" was accepted for The Second ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large. This is the first paper coauthored by Marcus Crestani, Markus Schlegel and I (all from Active Group GmbH) and given the time constraints I’m quite happy how I turned out. We’re super happy – contributing to an ICPF-related event in some small capacity is something I never thought I would be able to do.