While I don't disagree with you that ESR has a strong ideological tilt, it's also useful to remember that he wrote that quite a long time ago now, when that eff

While I don't disagree with you that ESR has a strong ideological tilt, it's also useful to remember that he wrote that quite a long time ago now, when that effectively =was= true. Going back to the subject at hand, I think that the post misses the point that being a 'hacker' isn't really about how many languages you know, it's about certain ways of thinking. The most important, IMO, things to know are all (fairly) language agnostic - algorithms and data structures. If you don't understand those and how they work and how to choose between them, then you're never going to be really good at what you do. Also, you need to learn a functional language well enough that you can solve hard problems using it. Understanding functional programming and all the concepts it introduces (partial evaluation, currying, monads, first class functions, map/reduce to name a few) will do wonders for how you write code in other languages and will make the code you write far cleaner and more readable and easier to extend afterwards.