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Jane Street's sneaky retention tactic
- rapind 1y agoMy sneaky retention tactic is Elm... I'm only retaining myself though :)
- melling 1y agohttps://archive.ph/u10ol https://archive.ph/u10ol
- akamaka 1y agotldr: OCaml
- canyp 1y agoThat programming language your doctor doesn't want you to know about.
- libraryofbabel 1y agoThe article isn’t really very persuasive about this though. Having worked with OCaml at Jane Street is not, I think most of us would agree, going to be, going to be a serious barrier to getting hired to work with another language somewhere else. > For Jane Street’s technical rank-and-file, particularly the many hired straight out of university, non-compete agreements may be surplus to requirements. A scan of jobs listed by Millennium, a rival fund that has recently clashed with Jane Street in court, shows the strength of the latter’s position in the job market. Millennium wants engineers experienced in c++, Go, Java and Python, languages that are commonly used across finance and tech. OCaml developers, it seems, are Jane Street’s to keep. If someone worked with OCaml at Jane Street I would just take this as a signal that they are smart enough to quickly learn Go, Python, whatever they need, and will probably be more successful after 6 months than a “Python developer” would be.
- yawaramin 1y agoSure you would, but would Millennium or other high-caliber firms? It seems they want engineers with C++ experience and that's not exactly 'easy' to pick up 'quickly'.
- odyssey7 1y agoI've experienced this while leaving a different company that used a rare language. It's a tough situation being experienced in <peculiar language for Company A> when you need to ace technical interviews in <mainstream language for Company B>. Once you have a few years of promotions, it gets even tougher when you need to compete with <mainstream language> senior+ software engineer candidates at the destination company. Maybe <flashy brand name> was enough to land the interview, but experience mismatches and limitations can remain apparent in the interview itself.
- afrisch 1y ago> Having worked with OCaml at Jane Street is not, I think most of us would agree, going to be, going to be a serious barrier to getting hired to work with another language somewhere else. The retention factor is *not* that other companies wouldn't want to hire them, but rather that these employees are likely to dislike being forced to use something other than OCaml.
- udev4096 1y ago[flagged]
- adamnemecek 1y agoIt’s not obscure.
- hotshot1001 1y agoto the users of this site probably not, but it is also only used by 0.8% of developers extensively [1]. [1] https://survey.stackoverflow.co/2024/technology https://survey.stackoverflow.co/2024/technology
- adamnemecek 1y agoObjective C is at 2.1%, defo not an obscure language.
- suspended_state 1y ago[dead]
- deleted 1y ago[deleted]
- mpalmer 1y agoAuthor doesn't seem to understand that skilled programmers can be productive in almost any language. Experience in the domain is more important.
- IshKebab 1y agoBut it's probably true that the developers who want to write OCaml have nowhere else to go really. And they're probably smarter on average than the average C++ developer. Still... I seriously doubt this is much of a consideration for why they use OCaml.
- galangalalgol 1y agoI can see it working for an opposite reason. Someone who has been paid decently to write mathematically challenging software in an interesting and ergonomic language would probably want a premium to go somewhere they use a boring annoying language to solve lots of trivial problems. It is an extension of why game dev and to a lesser extent, embedded dev, pay less than full stack even if they are typically more challenging.
- learningstud 1y agoLesser pay is simply due to less demand. It simply reflects the overall needs of living people.
- owl_vision 1y agoMany years ago, I interviewed with Jane Street. They asked me C++ questions and if I am willing to learn OCaml. Sure, I can learn any language. The position was given to someone else who already knew OCaml. They use OCaml for everything, building software to distributing it etc. That's my interview experience with them. I think they chose that language because it can be as speedy as C++ with proper knowledge and optimizations. I do not know OCaml besides learning it when I worked with researchers/mathematicians who wrote OCaml and i had to understand the code.
- rafaelmn 1y ago
- dmillar 1y agoGoldman has done this for decades, pushing it even further by having developed their own language (Slang), graph db (SecDB), and IDE (SecView). Many engineers resist working it in, but for any strat it's mandatory.
- marssaxman 1y agoWhat is a "strat"? I would never want to work for a place like Goldman anyway, but knowing they had their own idiosyncratic tech environment would certainly be an additional negative.
- __float 1y agoIt's a tech/quant role.
- marssaxman 1y agoA job title, then...? I took it for a description of the company; web search turns up only references to guitars and some hotel in Las Vegas.
- dmillar 1y agoStrats as a role has been downplayed and realigned a lot over the last several years. Traditionally, a strat was indeed a "quantitative strategist" that sat on the desk, often next to voice traders, developing tools, pricing models, trading systems, etc. One of the people I regard as the Godfather/OG strat is Emanuel Derman (https://emanuelderman.com/ https://emanuelderman.com/). Another transformative (in my time) person in the Strat complex was Marty Chavez (https://www.rmartinchavez.com/ https://www.rmartinchavez.com/). Both amazing people on and off the trading floor.
- markasoftware 1y agoit means "strategy". I imagine each "strategy" looks at some data and decides what kinds of trades to make in response, or predicts the price of some securities and sends that to a downstream process which decides what trades to make based on those price predictions.
- mpalmer 1y ago"Hedge funds will go to great lengths in pursuit of profits, whether it is by counting cars in satellite photos of parking lots or shipping gold across the Atlantic. Building a compiler—a piece of software that turns human-written code into programs a computer can execute—for your homegrown language? That still raises eyebrows." Cringeworthy. Quant funds do in fact work on things like this. It's not that crazy.
- jphoward 1y agoI don't think you know what "cringe" means... this really makes you cringe? And they didn't say it was crazy, they said it was interesting enough to raise eyebrows. Everyone knows there are amazing coders in hedge funds, but not many hedge funds have forked a language - it is worthy of discussion here.
- mpalmer 1y agoI think you're reaching for an interpretation of what I said that's easier to challenge. Once you explain to the average person what a compiler is, they can draw a straight line from writing the compiler to the hedge fund reducing risk, gaining a competitive edge, whatever. But this writer is choosing to hold up custom compilers as even more of an oddball move than counting cars, or shipping gold overseas. It's lazy writing from someone who is mistaking their lack of technical knowledge for common-sense insight into how strange software is. It is cringe.
- 1980phipsi 1y agoSymmetry investments had a similar relationship with the D language.
- owl_vision 1y agoIt is fair competition. Using the same tools as one's competition yields similar gains. Using better tools increases the possibility of higher profits. Same as in manufacturing, chip making: better tools more profit. Potentially better profit. Nothing cringey about it.
- brcmthrowaway 1y agoWhats the WLB balance like at JS? I would have loved to be making $1mn straight out of college!
- incognito124 1y agomore like work-work balance
- udev4096 1y agoNone whatsoever. Unless you have no life, it makes no sense to work for them
- nesarkvechnep 1y agoThe people who work at Jane Street are not OCaml developers, even though some of them work on the language. They’re software engineers which are most probably smarter than your average $LANG developer.
- b0a04gl 1y ago[dead]
- OutOfHere 1y agoThis tactic won't work so well anymore in the age of LLMs. With the exception of horror movies like C and C++, is now very easy to learn and work with a new language by learning it on the go while working with it using an LLM. One can and should ask an LLM a dozen questions to explain what is happening. Expertise absolutely still matters, but less than it did before.
- learningstud 1y agoLLM or not, most programmers cannot think straight. LLMs just lead to more false impressions of understanding. When LLMs become really good, they will refuse doing your work for you out of distaste.
- rwmj 1y agoSomehow I don't think you're going to be a candidate for Jane Street.
- OutOfHere 1y agoNo, rather, Jane Street is not a candidate for me. Anyone who is actually smart can trade on their own and make a good living, and doesn't need to work for a company that does it. By corollary, anyone who works for someone else's trading firm is not actually so smart.
- elbear 1y agoOr it just they didn't think they can make it on their own, so they didn't develop the necessary expertise.
- kqr 1y agoLLMs are not so good at less popular languages. They know the basics but they also quickly get confused.
- furyofantares 1y agoIt's always been pretty easy to learn any language "on the go" if dropped directly into a functioning codebase, with practical tasks to undertake in it. Even the "horror movie" languages you called out which obviously many many people have learned. LLMs do make it easier, essentially by giving anyone the opportunity to to drop into a working codebase and take on practical tasks inside it. I think 15 years ago I would have called out the imperative/functional divide as an exception, and that probably does still add challenge. But programming languages have progressed a lot, with imperative languages exposing you to a lot of functional concepts and functional languages having better ergonomics around state/IO.
- ttoinou 1y agoWe learn OCaml in CS classes at écoles préparatoires (CPGE MP) in france. It’s an amazing language, practical to implement the CS math oriented theory we just studied. Doesn’t work that great as a retention tactic to stay forever at university though
- londons_explore 1y agoLots of universities teach Haskell as part of a CS degree, and that has not too much use in the world outside academia...
- typesarecool 1y agoIt does have some places! I used it at IOHK, they use it at Mercury, a little at Meta, Galois, etc...
- Ambroisie 1y agoI'm still in love with Caml from my time in prépa, one of the reasons I'm sometimes eyeing JS for a move.
- fmajid 1y agoI had Serge Abiteboul and Xavier Leroy (author of OCaml) as TAs, teaching ML. The only effect was a deep and abiding hatred for the language.
- ttoinou 1y agoAh maybe we didn't go as deep as you into it ahah
- deleted 1y ago[deleted]
- joshmarinacci 1y agoThis is kind of a weak and fluffy article coming from the Economist. As a long term subscriber I’m disappointed.
- rahimnathwani 1y agoIf you don't like weak and fluffy, perhaps skip this week: https://www.economist.com/science-and-technology/2025/06/27/is-being-bilingual-good-for-your-brain https://www.economist.com/science-and-technology/2025/06/27/...
- diekhans 1y agoThe article doesn't understand programmers. People will stay because they are passionate about OCaml and there are not a lot of OCaml jobs. When hiring for a permanent position, I have the expectation that a programmer can learn a new language and environment. An OCaml programmer for a position that is python or C would be looked on very favorably. Far more attention-getting than “full-stack programmer”.
- neandrake 1y agoIf your only professional experience is OCaml and you want to look elsewhere for work then your opportunities shrink noticeably. Especially if you're looking for a position that requires experience. It's much more digestible for a company to hire someone out of college and invest in training on tooling. But many companies won't get past the resume if a senior developer has to take more time to on-board.
- learningstud 1y agoThe OCaml people probably know C/C++ better than most C/C++ programmers. Do you even know any of them?
- diekhans 1y agoThis is likely true for many companies. However, it is also a metric for what type of working environment it will be. I value being able to learn quickly and creativity over pre-training.
- markasoftware 1y agoHaving worked in the quant industry outside of JS, and being good friends with a couple JS employees, I'm of the opinion that in 2025 ocaml is hurting JS more than it helps them. Using an obscure programming language absolutely can help out your hiring effort at a small company; for example, I did an internship at quite possibly the only US-based company doing Common Lisp that hired undergrad interns. All my coworkers were extremely talented because (a) people who use Common Lisp are definitely PL enthusiasts rather than your typical FAANG-oriented CS college student and (b) without anywhere else to really go for an internship, they all ended up at this company and (c) they only needed a few interns so could afford to select only those who had prior common lisp experience. But Jane Street is big enough now that 90%+ of their software hires aren't joining /because/ of ocaml, but in spite of it. The well of existing ocaml (or more generally, functional programming) enthusiasts who are qualified and willing to work for JS has been depleted for some time now. Rather than ocaml being a sort of shibboleth to hire only engineers who are passionate about programming languages, JS now hires the same sorts of engineers who would work at any other quant fund (ie, generally smart CS students who grinded C++, python, and leetcode questions in college), offers them slightly more money and a slightly nicer office than their competitors, and sends them all through a 2-week ocaml bootcamp. but oh well, maybe ocaml is still worth it for the 10% of hires who actually are FP enthusiasts and would have otherwise gone into academia.
- delacy_essex 1y agoEhh idk I think there’s a sufficiently large group of people who like not just OCaml but also Rust, Haskell, Lisp, Elm, etc. It’s like a diaspora of programming language nerds.
- markasoftware 1y agoat least for the new grad pipeline, I'm gonna stick with 10% as my number for all PL enthusiasts combined.
- ekunazanu 1y ago> In 2025 ocaml is hurting JS more than it helps them Hurts them how though? Is there no other merit to OCaml other than serving (or having served) as a tool to filter out new hires?
- scarface_74 1y agoThis is similar to Epic Systems (the healthcare SaaS company) and Mumps.
- erikig 1y agotldr: OCaml and no non-competes
- jxjnskkzxxhx 1y agoIt's not a tactic. The story was that at one point the tech person in charge wanted to use ocaml because he liked it. The project was a success and there was never any reason to change it. I'm sure everyone here is familiar with these two phenomena of the corporate world: A) techie pushes tool not because it's useful or necessary but because he wants to learn the tool B) something that started as happenstance ends up as a defining property of critical infrastructure.
- pavel_lishin 1y agoWe're currently (very slowly) working to deprecate our Elixir codebase. I wasn't around when it was adopted, but it definitely felt like someone joined the company, evangelized Elixir, hired maybe half a dozen people who were really good at it, and then left. Eventually, our Elixir experts evaporated, leaving maybe two people who truly understand it and can do difficult work in it. That's not sustainable. Someone else in the comments here said that a good developer can be productive in any language, and that's true - but why hobble people? It's like saying a good surgeon can be productive with a butterknife and a pot of boiling water, or a good artist can be productive with a charred stick.
- hollerith 1y agoInteresting. So the people you already have can't just learn Elixir to the required standard.
- learningstud 1y agoThis speaks volumes of why the Elixir people left in the first place. As a separate point, if a company wants the most generally applicable programming language, there is no reason to look further than C, yet few companies are like this.
- hollerith 1y agoInteresting. So the people you already have can't just learn Elixir to the required standard or rather doing so is not in their self-interest.
- odyssey7 1y agoIf they've managed to escape Python for machine learning tasks then it's worth it imo.
- transpute 1y agoJane Street's reported use of LLMs + OCaml, https://archive.is/HSVJN https://archive.is/HSVJN > Using Vcaml and Ecaml, they wired AI tools straight into Neovim, Emacs, and VS Code.. RL Feedback: The system learns from what works, tweaking itself based on real outcomes.. Jane Street records the [developer] journey — every tweak, every build, every “aha!” moment. Every few seconds, a snapshot locks in the state of play. If a build fails, they know where it went south; if it succeeds, they see what clicked. Then, LLMs step in, auto-generating detailed notes on what changed and why. It’s like having a scribe for every coder, building a dataset that’s not just big — it’s relevant. For niche languages or closed-off systems, this could be the future.