What the interns have wrought, 2025

Summary

Yet again, we’re at the end of our internship season, and so it’s time to summarize what the interns were up to! This year, I was recommended a real bumper crop of exciting projects to include. It’s kind of crazy how many great intern projects are out there. To mention a few that I’m not going to have time to cover in detail: Annie Hu spent a big chunk of her summer investigating, implementing, and optimizing different neural net sequence models, trying out a variety of compilation techniques and toolchains. Aster Oransoy added build priorities to our build systems’ shared action execution service, so you can ensure low-priority builds don’t slow down high-priority ones. Allen Pei wrote a quickcheck-like system for creating automated tests of trading systems by generating randomized sequences of market events, along with shrinking heuristics for creating minimal test cases. Evan Thompson wrote an LSP for our inline CSS syntax extension which includes a CSS validator that found tons of instances of invalid CSS in our applications. Zhibo Chen added a generic form of optional arguments to OCaml, so that it can use other types than the traditional OCaml option type (including more efficient representations) for optional values. Conor Kennedy added predicate pushdown to our internal data warehouse system to do filtration before it gets to the full query engine, and even wrote a mini query planner for analyzing filter expressions to derive narrower key ranges. Joe Cutler worked on using JIT-ing to make our HardCaml simulator fast enough to be competitive with Verilator, but with much better start-up times. And those are just the ones I felt like I could explain in a handful of words each! As usual, I picked just three projects to go into in more detail. In particular: Leo Gagnon wrote a (sometimes dramatically) more efficient evaluator for JSQL, our internal SQL dialect that we use for lots of different user-facing tools. Aryan Khatri built a new version of our OCaml torc...