Presumably Jane Street didn’t choose C++ because they wanted to reduce bugs introduced by the preservation of state; the killer of prop shops. F# was developed six years after their founding, hence too young, and more importantly, a Microsoft-owned clone of OCaml. I don’t think it even ran on Linux before 2015. Today, F# might just suit the job, assuming you are open to being locked into the .NET family. An interesting idea to say the least.

Why C++ now? Still the fastest and tons of quants and highly skilled programmers know it. When you consider the correlation between C++ developers’ technical acumen and quantitative skills, coupled with the maturity and increasing convenience of the ecosystem, it makes sense.

> assuming you are open to being locked into the .NET family

Which is not different than being locked into e.g. JVM family, or even being locked into OCaml itself.

.NET (redone as Core) was a much worse choice 20 years ago than it is now of course. If they would fully open up the debugger, I would prefer it over the JVM. OCaml is more open (for .NET Core, there is still no good open debugger and the JVM suffers from Oracle keeping closed performance enhancements which, in my experience, do make big difference) than either of them, but not many people like programming it so it is hard to find people.

Everything in the C++ ecosystem is better now than it was 20 years go. The language, the tools, the libraries, the build systems. It's actually fairly pleasant to work in these days.

Not really, everything related to app development is just gone, dead, with Qt and wxWidgets being the remaining survivors.

VCL is only available to corporate shops and those that aren't into FOSS religion.

MFC is in maintenance mode, and so far Windows developers are more keen moving into one of .NET UI stacks while keeping some C++ code as COM/DLLs or even C++/CLI, than jumping into UWP/WinUI. It remains to be seen if WinUI 3.0 will change the migration trend.

Then on mobile OSes, it isn't even an option, unless you want to write your own GUI from scracth using OpenGL/Metal/Vulkan.

I doubt HFT firms are writing apps in C++.

Everything in almost every ecosystem is better than it was 20 yrs ago. Even Common lisp is evolving... even c++ is almost, aaaaalmost has a package manager :-)

G-Research in London are using F# I believe