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?

Still... I seriously doubt this is much of a consideration for why they use OCaml.

I've swapped a decent number of tech stacks throughout my career. When I haven't used a stack for a few years it took months to get up to speed. Especially at a senior level where I should be capable of making design decisions, codebase level technical improvements, team workflow optimization, etc.

Obviously domain knowledge is important but I wouldn't trivialize technical side.

They continued with their own db for decades out of inertia and also it worked fine. I think they've long since switched to TCP/IP and the public internet (for a time there was a Bloomberg network parallel to the public internet).

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.

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.

I wouldn't say Yaron Minsky was pushing OCaml because he wanted to 'learn' it. By that time he had already written the most popular PGP key exchange server...in OCaml: https://github.com/SKS-Keyserver/sks-keyserver/graphs/contri...

[1] https://survey.stackoverflow.co/2024/technology

> 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.

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.