Does anyone know of Rust in HTF teams? I think Haskell and OCaml may also be a good fit (and I know for a fact those are used in HFT teams).

Not sure whether this counts but someone did post their experiences of it on reddit.

https://www.reddit.com/r/rust/comments/bhtuah/production_dep...

From job ads I saw a year ago, there's at least one company in London doing HFT Rust.

Also, if memory serves, one of Lawrey's ex-colleagues has written his own version of Chronicle in D that's being used somewhere too.

D seems like it would be a great choice for HFT. You get the productivity of GC when you want it and then you can have @nogc for critical sections of your code base.

I think that's exactly what they did. The video is up on youtube from DConf 2017/8 IIRC.