[Text available only in English] In functional programming, fold refers to a family of higher-order functions that analyze a recursive structure through use of a given combining operation, recombine the results of recursively processing its constituent parts, building up a return value.

Map represents an associative abstract data type composed of a collection of key, value pairs.

This is exactly what is happening with the cultural scene at the very moment. We systematically and methodically change concepts, mix online and...