This is probably the first time I've seen K mentioned outside Project Euler or similar place. Kudos! As far as Python's popularity through readability is concerned, I'd add one extra facet related to readability: it makes writing tutorials, and learning/teaching in general, much easier. It also makes post-intermediate resources more available and treated by multiple people, even as blog or SO posts. Few languages can match it in that regard. Power is important, but for every hacker determined to program something using only folds and flips or what have you, there's a thousand people who are unlikely to need stuff beyond Think Like Computer Scientist and a decent level of reading comprehension (for mentioned blogs or SO posts if anything). I'm saying it as a fan of both Haskell and Python.