I have been working with Python for more than fifteen years and I developed very big systems with this language, learning to know and love both its power and its weaknesses, admiring its gorgeous object-oriented system and exploring some of its darkest corners.
Despite being so committed to this language (both for personal choices and for business reasons) I never stopped learning new languages, trying to get a clear picture of new (or old) paradigms, to explore new solutions to old problems and in general to get my mind open.
Unfortunately introducing a new language in your business is always very risky, expensive and many times not a decision of yours only. You are writing software that other may have to maintain, so either you evangelize your team and persuade other to join you or you will be forced to stay with the languages shared by them. This is not bad in itself, but sometimes it is a big obstacle for the adoption of a new language.
One of the languages I fell in love (but ... more