Jane Street open sourceed their production compiler for OCaml¹², which focuses on performance and correctness. It is called OxCaml, a fast-moving set of extensions to the OCaml programming language.

Highlights:

OxCaml's primary design goals are:

• to provide safe, convenient, predictable control over performance-critical aspects of program behavior
• but only where you need it,
• and ... in OCaml!

OxCaml's extensions

Our extensions can be roughly organized into a few areas:

• Fearless concurrency: Writing correct concurrent programs is notoriously difficult. OxCaml includes additions to the type system to statically rule out data races.
• Layouts: OxCaml lets programmers specify the way their data is laid out in memory. It also provides native access to SIMD processor extensions.
• Control over allocation: OxCaml gives programmers tools to control allocations, reducing GC pressure and making programs more cache efficient and deterministic.
• Quality of life: OxCaml also contains some extensions that aren't specifically about systems programming, but which we've found helpful in our day-to-day work

I'm so admired as a Scala Native coder. The good news is that I've been thinking about similar things for Scala Native for a long time and trying to do so. The bad news is that I may don't have the necessary resources or free time. However, I think OxCaml is a great project to follow and learn from.

Python is still great because of its community and reflections. In the community we have a lot of smart people sharing their knowledge and insights.

• 🌟 Playground Wisdom: Threads Beat Async/Await

Updates on July 26, 2025

The next article in the series is out:

• 🌟 From Async/Await to Virtual Threads