I had an amazingly fun week at ICFP/SPLASH in Singapore; it was the first time that these two major programming languages conferences were held simultaneously. My submissions turned into a bit of a success disaster; I ended up chairing a workshop, giving several talks and a keynote, and organising a tutorial, and helping out a bunch of colleague and students. And if this wasn't enough to fill up the week, collaborators I hadn't seen in a few years were also presenting a tonne of interesting work, so there was no time to breathe!

So much went on that I've split up the post into a five parter:

• Part 1: Chairing the 2nd Programming for the Planet Workshop
• Part 2: Holding a tutorial on OxCaml
• Part 3: Migrations to OCaml 5 with Jane Street and Docker
• Part 4: My case for post-POSIX IO being important for runtime designers
• Part 5: What I learnt from other people's talks and chats

Other colleagues who wrote up their experiences at ICFP 2025 include:

• Max Carroll wrote up his five days at ICFP.
• Patrick Ferris got lots of hacking done in his recap of the week!
• David Allsopp gives us his reflections on ICFP25 as well.
• Sadiq Jaffer recapped his ICFP 2025 talk on OCaml and AI.
• Chris Armstrong described his first ICFP experience and his talk.

References

• Madhavapeddy (2025). Holding an OxCaml tutorial at ICFP/SPLASH 2025. 10.59350/55bc5-x4p75
• Madhavapeddy (2025). What I learnt at ICFP/SPLASH 2025 about OCaml, Hazel and FP. 10.59350/w1jvt-8qc58
• Madhavapeddy (2025). It's time to go post-POSIX at ICFP/SPLASH 2025. 10.59350/mch1m-8a030
• Madhavapeddy (2025). Programming for the Planet at ICFP/SPLASH 2025. 10.59350/hasmq-vj807
• Madhavapeddy (2025). Jane Street and Docker on moving to OCaml 5 at ICFP/SPLASH 2025. 10.59350/3jkaq-d3398