> using functions as first-class-values This is called higher order functions (HOF). FP is a --in my humble opinion-- broader topic describes a certain progr

> using functions as first-class-values This is called higher order functions (HOF). FP is a --in my humble opinion-- broader topic describes a certain programming style. HOF is one thing in there, but so are "function+data rather then classes" and "favor immutability". In contrast the imperative programming style is not merely about "not having HOF" or "mutable variables all over the place".