The basic set of more expressive operations (like map, filter, and reduce/collect) are not "clever", they exist in lots of "boring" languages, not just languages like OCaml and Scala. It is true that their semantics must be learned, but this is also true of the semantics of for, while, if, switch, function(), object.method(), etc. etc. We don't lament that learning how function calls work is lengthening the ramp-up time of people who already know how to write straight-line code and jumps.
Yeah, I think the charge of "clever" is often thrown out when one uses a different way of thinking. I'm not an FP zealot at all, but I do think learning to think recursively does something to one's programming. (Working through SICP or even The Little Schemer) My own personal take it that I appreciated and enjoyed some of those paradigms far more. What I would NEVER try to do is turn Java or Go into those paradigms though. I would, however, like to have some of those handy niceties available by default. (I want to map over a collection and apply a function to each member). But again, that's a personal preference.
It is idiomatic in Java to use the streams api for mapping, filtering, and reducing. It is a perfectly natural fit in the language. The only bummer is that those operations can't be built directly into the collections api due to compatibility concerns. It doesn't require thinking recursively or anything clever or advanced, they are very simple operations.
The irony is that even modern Basic is a clever language, and Python comprehensions are probably a PhD level feature, yet primary school children seem very at ease with those languages.
