There's one perspective (popular in funtional programming circles) that says data structures simply _are_ a special sort of function; that is, one that take no

There's one perspective (popular in funtional programming circles) that says data structures simply _are_ a special sort of function; that is, one that take no arguments. Really, in practice this means data is a partially applied, curried, identity function. Put something in, get the same thing out later, acting as memoization.