This is going to be fun! I know he's joking, but I agree-- to a point. First, if you write Haskell-in-Java code, you're going to do a horrible job unless you

This is going to be fun! I know he's joking, but I agree-- to a point. First, if you write Haskell-in-Java code, you're going to do a horrible job unless you have so much autonomy that you end up reinventing Scala... in which case you should just use Scala. (See: Greenspun's Tenth Rule.) Second, I think you learn a lot by studying other languages, but most of the superiority of Lispers or Haskellers comes from the fact that good programmers in general tend to be a curious set. Learning Lisp will make you a better Python programmer, and possibly a better C++ system architect. Will it make you better as a subordinate grunt on a gigantic C++ codeball? No, absolutely not. It will make you a morale problem and get you fired. Third, you learn a lot more in expressive languages that makes you a better programmer but the languages itself don't get all the credit. When you use a Lisp, you can get a lot done quickly if you know what you're doing and cover a wide swath of computer science. When you use a true fringe language, you end up implementing a lot of libraries you'd just assume work in Java. These experiences are highly valuable but not rooted in the languages per se. It's just that a lot of the work you have to do to make a non-mainstream language usable in primetime contributes to your long-term awesomeness growth. Fourth, if you want to be a Corporate Programmer (TM) and not be challenged too much, then maybe get tapped for management in your mid-30s, then Haskell and Python will poison you. I've written a lot about the progress of developer competence (see this, just today: http://michaelochurch.wordpress.com/2013/04/22/gervais-macleod-23-the-shodan-programmer/ http://michaelochurch.wordpress.com/2013/04/22/gervais-macle... ). Once you cross the 1.4 rubicon, there really is no going back, and you'll be in conflict with managerial authority forever. Well, at least until you become so good that it's eminently obvious and you can escape the CrapFactory (or is it CrapVisitorSingletonFactory?) Corporate Programming world. However, if what you want is to be a great programmer (not an easily employable one) then Haskell and Python will do you favors, and learning a few more languages (also C, because the low-level will always be important for some domains) is probably necessary. This was written in 2006; I wonder what he'd think of JVM languages, especially Clojure.