Speaking of OCaml, I'm currently working through the Real World OCaml book [1] by Yaron Minsky, Anil Madhavapeddy and Jason Hickey, who are some of the drivers of using OCaml in production settings (Yaron Minsky works for Jane Street, who aside from being a quant firm are also the developers of the popular Core alternative standard library).

I highly recommend it.

[1] https://realworldocaml.org/