I stand in front of you, in total disbelief, as head of the department for which Eelco Visser has worked the last 15 years.

I would like to offer you my perspective on Eelco’s significance, as a scientist, as a teacher, and as a person.

Eelco and I got to know each other in 1992, thirty years ago.

At the time, I was halfway my PhD in Amsterdam, working in the group of Paul Klint. Eelco was studying in Amsterdam, following Paul’s courses. These were so inspiring to Eelco that he decided to join Paul’s group, first to write his master’s thesis, and then to work on his PhD.

It didn’t take long before Eelco and I had a connection. We had extensive discussions about research. The details don’t matter, and they didn’t really lead to concrete results. But thirty years later I still remember the substantive drive, the deep desire to profoundly understand a problem, the feeling to work on something very important, and, of course, Eelco’s tenacity.

Eelco has been able to maintain that same drive for thirty years. Just like he knew how to inspire me, year after year he has inspired his students and his (international) peers — always driven by content, always persistent.

This contributed to Eelco’s research being of the highest international level. Let me illustrate this through an award he received in 2020, a so-called Most Influential Paper award. This is an award you get ten years after publication, after it has been established that your paper actually had made the biggest impact.

Eelco received this award for his article from 2010 on Spoofax, written with (then) PhD student Lennart Kats. Eelco was very proud of this award, and rightly so. In fact, he was so proud that he wrote a (long) blog post about it, entitled “A short history of the Spoofax language workbench.”

This “short history” starts in 1993 with Eelco’s PhD research in Amsterdam. Next, Eelco explains his journey, from Portland as a postdoc, via Utrecht as assistant professor, to Delft as associate and full professor. Each of these stops provides building blocks for the award-winning paper from 2010. And then, Eelco’s “short history” continues: He describes what his group in those ten years after the paper’s publication has done, and what good things he still has in store for the time to come.

To me, this “short history” is signature Eelco:

• Visionary, working year after year on building blocks that all belong together
• System-driven, with working software that he preferably contributes to himself
• In a team, together with his PhD students, postdocs, engineers, students, and numerous international co-workers.

This short history also serves to illustrate the international side of Eelco’s work. He was very active, and loved, within international organizations like IFIP and ACM SIGPLAN. He succeeded in bringing the flagship SPLASH conference to Europe for the first time.

And, naturally, Eelco had a vision on how to improve things: All those conferences putting effort in ad hoc web sites: There had to be a better way. And so, in line with his systems philosophy, he designed the CONF system that has been up and running for ten years now. And he managed to convince hundreds of conferences to use his system, for a fee.

Likewise, Eelco had a vision on education, and he knew how to realize it. In his opinion, programming education just had to be better. Thus, he designed a system, WebLab, which has also been in operation for almost 10 years now. And here too he managed to convince countless teachers to use his system.

In addition, Eelco had a well-thought-out opinion about the courses that belong in a computer science program. So when we needed to revise our curriculum, Eelco was the perfect candidate to chair the associated committee. Eelco did this graciously, in a calm and persistent manner, reasoning from educational principles to settle disputes. The result is rock solid.

Eelco’s education is well characterized by Willem-Paul Brinkman in the online Farewell Community: Without maybe realizing it, many generations of Delft students will benefit from his teaching innovations.

Eelco was proud of his Programming Languages Group. He built it up from scratch into an international top group. He took good care of his people, fighting for the best equipment and offices. As a member of the departmental management team, he fought for computer science in full, at faculty and university level. Nationally he was active in, for example, the Dutch National Association for Software Engineering VERSEN.

And how was Eelco able to realize all this? What was his secret?

Perhaps Eelco actually liked (a little) resistance. He was not afraid to disagree: after all, he had thought deeply about his opinion. And he was fine with being challenged: it was a sign that he was well on his way to breaking the status quo.

Maybe not everyone always found this easy. But Eelco was also very friendly, and certainly willing to change his mind.

And, Eelco was also patient: Big changes take time. If he saw that he had insufficient supporters, he could wait. Or, under the radar, start small in order to set his own plans in motion.

How much we will miss Eelco in Delft! The visionary, the obstinate, the focus on the content, the love for computer science, the tenacity, and the attention for students and colleagues: exactly what we need so much in Delft.

Let me conclude with a few words related to Corona and the lock down. The past few years, Eelco and I were in touch weekly, mostly within the departmental management team, but also often one-on-one. All online, from home. We discussed departmental matters, small and large, as well as the impact of Corona. On one thing we agreed: Being at home more, seeing more of your children, doing more with the family: we both experienced this as a gift.

Due to the lock down, I don’t know when it was that I saw Eelco last in person. I think it was on October 14, at the PhD defense of Arjen Rouvoet. This was a beautiful day, and this is how I like to remember Eelco: Science at the highest level, international peers in substantive debate, a cum laude PhD defense, and Eelco happy, radiant in the midst of his PL group.

Dear family, friends, colleagues, everyone: We will miss Eelco very much. Each of us has his or her own, wonderful memories of Eelco. Today is a day to hold on to that, and to share those memories with each other.

I wish you all, and especially the family, all the best.