[wkyleg]

I can see that.

On most metrics I've seen Rust is comparable on general speed.

Maybe if you're at the level where you've essentially writing portable assembly and are okay with lack of safety. You need to know exactly what is happening within the CPU, maybe on custom hardware.

I bet some defense applications would be in this category too, although for my own sense of self preservation I would prefer the Rust type system.

[gpderetta]

Rust would probably be a good fit for HFT, but as the field is so dominated by C++ is hard for another language to make inroads. Java managed to some extent.

I would expect a lot of unsafe though.

[cempaka]

Ecosystem effects are definitely important to C++'s dominance in HFT, but it's also a domain where a lot of the guarantees Rust offers just aren't all that relevant. From a security perspective most code always runs in sandboxes accessible to only a select few whitelisted IPs. True, you don't want a segfault while you're in the middle of sending an order to an exchange, but most of those are pretty easily smoked out in simulation testing.