I also predominantly use python and JavaScript professionally, but have written a lot of Haskell, and a bit of go, rust and others. I love haskell and GHC but

I also predominantly use python and JavaScript professionally, but have written a lot of Haskell, and a bit of go, rust and others. I love haskell and GHC but it's not a builder's language. That's not to say it can't be used in production, the language is very powerful, easy to refactor, performs well and is hard to make mistakes in. Some of the tooling like QuickCheck, STM and lenses are decades beyond other ecosystems whereas simple things like logging are hard and debuggers/autoformatters/IDE tooling are less polished than their counterparts in mainstream language. I have both Haskell and Django web applications in production and it pains me to say that python is a lot more convenient and easier to iterate on. Finally, in answer to your question I would recommend rust. It is a rising star with a decent type-system derived from ML languages. I would also characterise the language and it's ecosystem as being focused on building production software. As an added bonus it integrates well with python and JavaScript applications, and is a useful tool to have for optimising expensive algorithms.