[mybrid]

Perhaps a little more experience with teaching would enlighten. I taught programming for a year in college and you know what one of the hardest concepts was that caused test scores to drop? Recursion. People invariable struggle with base cases. Recursion is a key tool for software development albeit procedural or functional. Teaching software to students is a real eye opener if one never struggles with what may be seemingly basic concepts like recursion. I've seen students flunk tests because they couldn't grasp the concept. Another concept that is not quite is hard is callback functions. I believe this is why functional programming challenges is because lambda functions are callback functions. I have to admit if hadn't taught software at Berkeley for a year as a TA I wouldn't have this perspective so something to consider.