You don't use the new language exclusivity, it's just an extra tool in your toolbox. You just use it to expand your horizons. Knowing even a little Haskell will

You don't use the new language exclusivity, it's just an extra tool in your toolbox. You just use it to expand your horizons. Knowing even a little Haskell will show you that a little type inference can go a long way. Or that reasoning about correctness is easier in a purely functional language. I think the primary advantage of knowing many languages is knowing when you're using the wrong tool for the job.