I think you should take a close look at the ML family. Well, I'm not sure how good their concurrency support is; I doubt it's as good as Go's. But they have v

I think you should take a close look at the ML family. Well, I'm not sure how good their concurrency support is; I doubt it's as good as Go's. But they have very good compilers, and a reputation for being good for numeric work. They are strongly typed and garbage-collected, but differ from Haskell in giving you the option of writing imperative code when you want, and in generally having a more familiar programming model (they are strict, like most languages, rather than lazy). OCaml has a small but strong following in the financial services world -- it's used by algorithmic traders, who are known to be performance-sensitive, to put it mildly. And Standard ML has the MLton whole-program optimizing compiler. I have to qualify this by adding that I haven't used either of these tools myself, but for certain kinds of problems, I would definitely give them a closer look.