I subscribe to R-devel, the email list where R core development is discussed.

Last Friday R-4.6.0 was released. This is a big release with breaking C API changes. Peter Dalgaard wrote that its codename “Because it was There” was chosen in rembrance of R Core member Tomàš Kalibera (1978–2026).

I was surprised and saddened to hear of the passing of Tomàš. Jan Vitek wrote an obituary.

I met Tomàš once in person, at useR in Brussels, 2017.

Since then I had several interactions with Tomàš on R-devel, notably in 2019. While working on timing comparisons for my R Journal paper about namedCapture for regular expressions, I noticed a performance issue, and I sent R-devel a bug report for substring and a patch for gregexpr. Tomàš Kalibera merged the fixes into R (since version 3.6 in 2019).

This is just one example of the tireless and impactful work that Tomàš put into R in the last 10 years. R is much better because of him, and his presence in the community will be greatly missed.