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...
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Using group theory to explore the space of positional encodings for attention
Attention is a computational primitive at the core of modern language models, allowing internal representations to reference and influence each other. It’s how these models...
By: Alok Puranik
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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...
By: Ricson Cheng
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Results from the Advent of FPGA Challenge
At the end of last year, we decided to try something new: a challenge that would run alongside Advent of Code, where we asked the...
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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...
By: Edwin Morris
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Fun with Algebraic Effects - from Toy Examples to Hardcaml Simulations
I recently ported the Hardcaml_step_testbench library, one of the libraries that we use at Jane Street for Hardcaml simulations, from using monads to using algebraic...
By: Fu Yong Quah
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Getting from tested to battle-tested
Testing is an essential part of building reliable software. It’s a form of documentation, a reminder of mistakes of the past, and a boost of...
By: Doug Patti
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Advent of FPGA — A Jane Street Challenge
Update: We got over 200 submissions to this challenge, spanning a wide variety of HDL languages and hardware platforms! We featured our favorite submissions in...
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What the interns have wrought, 2025 edition
Yet again, we’re at the end of our internship season, and so it’s time to summarize what the interns were up to!
By: Yaron Minsky
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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, called Gord....
By: Nikhil Jha
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Introducing OxCaml
At Jane Street, we’ve been actively making improvements to OCaml for a long time. Over the last few years, we’ve started to build some fairly...
By: Leo White
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Advent of Hardcaml
Update: For the 2025 Advent of Code, we ran an Advent of FPGA Challenge where we invited the community to implement their own synthesizable solutions...
By: Anish Singhani
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How we accidentally built 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...
By: Andrey Mokhov
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Developer education at Jane Street
Like most places, Jane Street largely teaches developers through a kind of apprenticeship model. A team matching process tries to thoughtfully match new devs to...
By: Aaron Bauer
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ICFP 2024
It’s no secret that Jane Street is an active participant in the programming language community, and we’re excited to be attending ICFP 2024, the International...
By: Nailen Matschke
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What the interns have wrought, 2024 edition
We’re once again at the end of our internship season, and it’s time do our annual review of what the interns achieved while they were...
By: Yaron Minsky
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Visualizing piecewise linear neural networks
Neural networks are often thought of as opaque, black-box function approximators, but theoretical tools let us describe and visualize their behavior. In particular, let’s study...
By: Ricson Cheng
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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...
By: Yaron Minsky
