At least 3! Lots more depending on your definition of “proficient”. “How do you be proficient if you study so many languages?” All programming languages are

At least 3! Lots more depending on your definition of “proficient”. “How do you be proficient if you study so many languages?” All programming languages are basically the same if you squint at them. Each language is better at different things, and can help you see code in different ways. Learning Haskell will help you write better JavaScript, for example. So really I think the opposite is true: how do you know you’re not boxed into a narrow way of thinking if you’ve only used 1 language? I am maximally productive in a small handful of languages because I use them the most and am familiar wit the idioms, pitfalls, libraries, etc. If you use other languages day-to-day I don’t think you’ll be able to maintain maximal productivity with Rust and Golang. But learning them can teach you alternative perspectives, or can give you a leg up if you encounter a problem to solve that lies within their sweet spot.