1
Formal methods and the future of programming
I’ve been telling people for the last 25 years that Jane Street as an organization was just not interested in formal methods.
Jane Street Tech Blog
OCaml and Systems rolled into one
- Popular posts
- 23
- Total points
- 4,786
- HN comments
- 2,431
- Rank
- #228 company
Visit blog.janestreet.com → RSS feedOn Hacker News Mar 2018 – Oct 2026
Software Engineering 15Tools & Productivity 5Programming Languages 5AI & Machine Learning 5Systems & Performance 3Career & Management 3
2
A better build system for OCaml
A “build system” is one of the most important tools in a developer’s toolbox. Roughly, it figures out how to create runnable programs from a bunch of differe...
3
I design with Claude more than Figma now
For a long time I was skeptical of LLMs—whenever I reached for them I was disappointed by the results. Last year I tried Copilot and Cursor to tweak a game I...
4
Can you reverse engineer our neural network?
A lot of “capture-the-flag” style ML puzzles give you a black box neural net, and your job is to figure out what it does. When we were thinking of creating o...
5
Putting the I back in IDE
Imagine a system for editing and reviewing code where:
6
Plans for OCaml 4.08
With the external release of OCaml 4.07.0 imminent, we in Jane Street’s Tools & Compilers group have been planning what we want to work on for inclusion ...
7
Oxidizing OCaml: Locality
OCaml with Jane Street extensions is available from our public opam repo. Only a slice of the features described in this series are currently implemented.
8
What the interns have wrought, 2020 edition
It’s been an unusual internship season.
9
A Higgs-Bugson in the Linux Kernel
We recently ran across a strange higgs-bugson that manifested itself in a critical system that stores and distributes the firm’s trading activity data, calle...
10
Deep learning experiments in OCaml
Last year we held a machine learning seminar in our London office, which was an opportunity to reproduce some classical deep learning results with a nice twi...
11
What the interns have wrought, 2018 edition
Yet again, intern season is coming to a close, and so it’s time to look back at what the interns have achieved in their short time with us. I’m always impres...
12
Can you use autoregressive diffusion to generate market data?
The following is part of a series of posts about 2026 summer intern projects – for more, see “What the interns have wrought, special jumbo 2026 edition”
13
Commas in big numbers everywhere: An OpenType adventure
My job involves a lot of staring at large numbers, mostly latencies in nanoseconds, and picking out magnitudes like microseconds. I noticed myself constantly...
14
Magic-trace: Diagnose tricky performance issues with Intel Processor Trace
Intel Processor Trace is a hardware technology that can record all program execution flow along with timing information accurate to around 30ns. As far as I ...
15
Using Python and OCaml in the same Jupyter notebook
The cover image is based on Jupiter family by NASA/JPL.
16
L2 Regularization and Batch Norm
This blog post is about an interesting detail about machine learning that I came across as a researcher at Jane Street - that of the interaction between L2 r...
17
Strace-ui, Bonsai_term, and the TUI renaissance
We’ve always found strace useful but somewhat hard to work with. Its output is often inscrutable, it’s hard to follow subprocesses or threads, and if you wan...
18
What the interns have wrought, 2023 edition
We’re once again at the end of our internship season, and it’s my task to provide a few highlights of what the dev interns accomplished while they were here.
19
“Expect tests” make test-writing feel like a REPL session
At Jane Street we use a pattern/library called “expect tests” that makes test-writing feel like a REPL session, or like exploratory programming in a Jupyter ...
20
Can you reverse engineer an ASIC?
Earlier this year we published a puzzle that handed you a complete neural network and asked you to figure out what it did. The response was great, so we’ve made another one! This time, we’re going much deeper down the tech stack.
21
Formal Methods and the Future of Programming
I’ve been telling people for the last 25 years that Jane Street as an organization was just not interested in formal methods.
22
What is gained and lost with 63-bit integers? (2014)
Almost every programming language uses 64-bit integers on typical modern Intel machines. OCaml uses a special 63-bit representation. How does it affect OCaml?
23
Accelerating zk-SNARKs - MSM and NTT algorithms on FPGAs with Hardcaml
In 2022 a consortium of companies ran an international competition, called the ZPrize, to advance the state of the art in “zero-knowledge” cryptography. We d...