About Being a Polyglot Software Engineer
sap1ens.com
sap1ens.com
I know Python well. I know Django well. Those cover 90% of my needs as a programmer and the libraries are usually of a decent quality (compared to my experiences in JavaScript for example) so why would I introduce a new language? I will write better quality Python/ Django code because I know the idioms, and best practices, I know how to write clean code. If I switch to another language, sure I will be able to write the same, but the quality of my code will not be as high and it will take me longer.
I don't think knowing more languages is a bad thing, but adding new languages to a project for the sake of it can be.
Python does support functional programming, but it's not a primary way of doing things. By learning one of the Lisp-like languages you can better understand all the idioms you would use in Python to apply functional programming concepts better.
You don't need to necessarily add it to you projects at work, it can be as simple as doing an online course.