Signals and Threads

Afleveringen

1. The Changing Craft of Programming with John Crepezzi

   16 oktober 2026 · 1 uur 48 min

   Afspelen
   John Crepezzi has spent his career building tools for other programmers—at Tumblr, at Square, and then at GitHub, where he worked on the merge queue and the early versions of Codespaces. He came to Jane Street to build a code search engine for OCaml. A week into the job, ChatGPT came out, and he’s been working on AI tooling ever since. In this episode, Ron and John talk about how a three-day prototype grew into a firmwide platform for agentic coding, how AI can break the social contract around code review, and how to build tools that support both agent workflows and human understanding. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   QBasic

   Pirates of Silicon Valley

   Hoogle — the Haskell API search engine that inspired the original code-search project

   GitHub merge queue and Codespaces

   Sorbet — gradual typing for Ruby; Hack — Meta’s typed PHP

   Active Record

   Bubblewrap and passt/pasta — sandboxing tools

   seccomp BPF

   Claude Code and OpenAI Codex CLI

   Model Context Protocol and Agent Skills

   Perfetto and magic-trace

   Antithesis

   Bonsai — Jane Street’s OCaml web UI library

   Signals & Threads: Language Design with Leo White

2. Learning Goals and the Goals of Learning: Teaching in the Age of AI with Aaron Bauer

   23 september 2026 · 1 uur 37 min

   Afspelen
   Aaron Bauer is a software engineer and one of Jane Street's few developer educators—a role that splits his time between writing code and teaching other people how to write it. Before joining the firm, he taught computer science at Carleton College, including four straight terms online during the pandemic. In this episode, Ron and Aaron discuss what it takes to teach engineering inside a company with its own language, its own version control, and its own editors, and what changes when an LLM can do the exercise for you. Along the way, they consider the underrated power of a live lecture; why the text editor is still the software engineer's home base; using editor telemetry to find out how AI is actually changing developer workflows; and how Jane Street rebuilt its intern curriculum around testing, design, and code review now that producing the code is the easy part. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Foldit and AlphaFold

   Carleton College Computer Science

   Flipped classroom, active learning, mastery learning, and cognitive load

   "The Pen Is Mightier Than the Keyboard" — Mueller & Oppenheimer on handwritten vs. typed notes

   Merlin and ocaml-lsp

   ecaml — writing Emacs extensions in OCaml

   Bonsai — Jane Street's OCaml web UI library

   OxCaml

   Claude Code output styles — the "learning" mode Aaron describes (note: Anthropic has since moved this to a plugin)

   Jane Street's tech internship

3. Wrestling the world into rows with Eric Mannes

   2 september 2026 · 1 uur 25 min

   Afspelen
   "Alternative data" is Wall Street's name for information that comes from non-traditional sources: satellite photos of parking lots, credit card panels, weather forecasts. Eric Mannes has spent over a decade at Jane Street, first as a commodities trader and now helping lead the firm's alternative data team. In this episode, Eric and Ron talk about what it takes to turn messy external data into datasets a trading strategy can rely on. Along the way, they cover the day oil futures settled at a negative price and the systems that broke as a result; the years when the commodities desk's risk system was one very large Excel spreadsheet; the hard question of what a company even is; and why better ML models raise the value of careful data engineering. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Figgie

   Adverse selection

   2020 Russia–Saudi Arabia oil price war

   Dual-listed company

   "LAMBDA: The ultimate Excel worksheet function"

   Trino

   The Bitter Lesson

   Learn more about Jane Street’s internship program.

   Apply for Data Engineering roles at Jane Street

4. Building a data warehouse from scratch with Jacob Baskin

   24 juni 2026 · 1 uur 34 min

   Afspelen
   In university Jacob Baskin studied at the intersection of computer science and economics, thinking about systems that incentivize people to express their true preferences. He put those ideas into practice at Google, where he worked on ad serving, before joining Jane Street’s database infrastructure team. In this episode, Ron and Jacob discuss Superstore, a distributed columnar database now central to Jane Street’s tech stack that Jacob began building practically the day he started. How do you support wide-ranging analytical queries while transactional writes stream in at the speed of trading systems? And what’s it like when your first design doc leads to an eight-figure hardware purchase? After building Superstore Jacob has since gone back to his roots, thinking about schemes for bidding on compute time as he works to optimize usage of the Hive, Jane Street’s massive compute cluster for research. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Mechanism design, second-price auction

   MapReduce, BigTable, Google File System

   Vertica

   Apache Parquet

   CockroachDB

   Paxos

   BitTorrent

5. The Network as a Program with Nate Foster

   1 juni 2026 · 1 uur 35 min

   Afspelen
   Nate Foster is a professor at EPFL in Switzerland in the Networked Systems Abstractions Lab, and a visiting researcher at Jane Street on the Networking team. In this episode, he and Ron consider what happens when you bring a software mindset to network engineering. Can you use programming language theory and formal methods to realize the dream of software-defined networks? Along the way, they discuss how hyperscalers have shaped networking hardware; the return (or not) of multicast; the ways ML workloads are reshaping the networking layer; and the success Jane Street has had using an early Internet protocol, BGP, together with a more declarative high-level specification language. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   P4 (Programming language

   Lenses (bidirectional transformation)

   OpenFlow

   Kleene algebra with tests

   NetKAT

   End-to-end principle

   Border Gateway Protocol

   “Stable Internet routing without Global Coordination,” aka the Gao-Rexford conditions

   Unison file synchronizer

   Barefoot Networks

6. Why Testing is Hard and How to Fix it with Will Wilson

   17 maart 2026 · 1 uur 48 min

   Afspelen
   Will Wilson is the founder and CEO of Antithesis, which is trying to change how people test software. The idea is that you run your application inside a special hypervisor environment that intelligently (and deterministically) explores the program’s state space, allowing you to pinpoint and replay the events leading to crashes, bugs, and violations of invariants. In this episode, he and Ron take a broad view of testing, considering not just “the unreasonable effectiveness of example-based tests” but also property-based testing, fuzzing, chaos testing, type systems, and formal methods. How do you blend these techniques to find the subtle, show-stopper bugs that will otherwise wake you up at 3am? As Will has discovered, making testing less painful is actually a tour of some of computer science’s most vexing and interesting problems. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Antithesis, Will’s company

   FoundationDB’s deterministic simulation framework

   QuickCheck — the original Haskell property-based testing library, by Koen Claessen and John Hughes

   Hypothesis — property-based testing for Python, created by David MacIver

   QuviQ — John Hughes’ company commercializing QuickCheck, including automotive testing work

   Netflix Chaos Monkey

   Goodhart’s law — “When a measure becomes a target, it ceases to be a good measure”

   CAP theorem — the impossibility result for distributed systems that FoundationDB claims to have in some sense violated.

   Paxos — the consensus algorithm FoundationDB reimplemented from scratch

   Large cardinals, an area Will studied before abandoning mathematics

   Lyapunov exponent — measure of chaotic divergence

   Chesterton’s fence

   The Story of the Flash Fill Feature in Excel

   Building a C compiler with a team of parallel Claudes

   Barak Richman, “How Community Institutions Create Economic Advantage: Jewish Diamond Merchants in New York”

7. Why ML Needs a New Programming Language with Chris Lattner

   3 september 2025 · 1 uur 13 min

   Afspelen
   Chris Lattner is the creator of LLVM and led the development of the Swift language at Apple. With Mojo, he’s taking another big swing: How do you make the process of getting the full power out of modern GPUs productive and fun? In this episode, Ron and Chris discuss how to design a language that’s easy to use while still providing the level of control required to write state of the art kernels. A key idea is to ask programmers to fully reckon with the details of the hardware, but making that work manageable and shareable via a form of type-safe metaprogramming. The aim is to support both specialization to the computation in question as well as to the hardware platform. “Somebody has to do this work,” Chris says, “if we ever want to get to an ecosystem where one vendor doesn’t control everything.” Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Democratizing AI compute (an 11-part series)

   Modular AI

   Mojo

   MLIR

   Swift

8. The Thermodynamics of Trading with Daniel Pontecorvo

   25 juli 2025 · 59 min

   Afspelen
   Daniel Pontecorvo runs the “physical engineering” team at Jane Street. This group blends architecture, mechanical engineering, electrical engineering, and construction management to build functional physical spaces. In this episode, Ron and Dan go deep on the challenge of heat exchange in a datacenter, especially in the face of increasingly dense power demands—and the analogous problem of keeping traders cool at their desks. Along the way they discuss the way ML is changing the physical constraints of computing; the benefits of having physical engineering expertise in-house; the importance of monitoring; and whether you really need Apollo-style CO2 scrubbers to ensure your office gets fresh air. Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers)

   Some research on CO2’s effects on human performance, which motivated us to look into CO2 Scrubbers

   The Open Compute Project

   Rail-Optimized and Rail-only network topologies.

   Immersion cooling, where you submerge a machine in a dielectric fluid!

9. Building Tools for Traders with Ian Henry

   28 mei 2025 · 1 uur 20 min

   Afspelen
   Ian Henry started his career at Warby Parker and Trello, building consumer apps for millions of users. Now he writes high-performance tools for a small set of experts on Jane Street’s options desk. In this episode, Ron and Ian explore what it’s like writing code at a company that has been “on its own parallel universe software adventure for the last twenty years.” Along the way, they go on a tour of Ian’s whimsical and sophisticated side projects—like Bauble, a playground for rendering trippy 3D shapes using signed distance functions—that have gone on to inform his work: writing typesafe frontend code for users who measure time in microseconds and prefer their UIs to be “six pixels high.” Lees meer

   You can find the transcript for this episode on our website.

   Some links to topics that came up in the discussion:

   Bauble studio

   Janet for Mortals, by Ian Henry

   What if writing tests was a joyful experience?

10. Finding Signal in the Noise with In Young Cho

    12 maart 2025 · 1 uur

    Afspelen
    In Young Cho thought she was going to be a doctor but fell into a trading internship at Jane Street. Now she helps lead the research group’s efforts in machine learning. In this episode, In Young and Ron touch on the porous boundaries between trading, research, and software engineering, which require different sensibilities but are often blended in a single person. They discuss the tension between flexible research tools and robust production systems; the challenges of ML in a low-data, high-noise environment subject to frequent regime changes; and the shift from simple linear models to deep neural networks. Lees meer

    You can find the transcript for this episode on our website.

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