You should learn multiple paradigms to broaden your horizon, so you are able to approach a problem from multiple angles and decide on the best design approach.

You should learn multiple paradigms to broaden your horizon, so you are able to approach a problem from multiple angles and decide on the best design approach. I don't write in a functional language in my day job, but I'm much more aware of global state and side-effects in my code than before. We mainly write in Python and C#, but I encourage my team members to dabble in SQL (for dataset manipulation) and Haskell (for functional purity). If anything, it makes them understand LINQ better.