I've been writing a lot of Golang in the last year and I wouldn't use it for writing a parser. It's just a modernised C, the model it provides is very simple (coming from C# the simplicity actually made it harder to learn!) and is very well suited to small, focused applications where a low conceptual load are beneficial and the trade off of verbosity are acceptable.

F# or even the latest version of C# are what I would recommend. Yes Microsoft are involved but if you're going to live in a world where you won't touch anything created by evil corporations then you're going to have a hard time. Java, Golang, Python, TypeScript/Javascript and Swift all suffer from this. That leaves you with very little choice.

I'd be interested in hearing your thoughts over OCaml after a year or so of using it. The Haskell-likes are very interesting but Haskell itself has a poor learning curve / benefit ratio for me (Rust is similar there actually; I mastered C# and made heavy use of the type system but that involved going very very deep into some holes and I don't have the time to do that with Rust).