The implication that Jane Street locks engineers into only getting experience with Ocaml isn't really true: most engineers there are competent enough to keep another language up to scratch through hobby projects if they wanted to; and somewhere like the mentioned Millennium could still hire someone from Jane Street even with only modest C++ experience (for example) because of their domain understanding, low-latency experience, and general transferable programming skills.

It's just true that a lot of the people there genuinely value getting to use a functional language. Also they pay well, the culture is pretty good, and if something goes wrong you can usually just switch teams, so there's really not a big reason to leave.

https://www.efinancialcareers.com/news/2023/04/goldman-sachs...