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5.5.2 Lists

A list is a sequence of zero or more objects, the main difference between lists and vectors is that lists are more dynamic: they can change size, be split, reversed, concatenated, etc… very easily.

In Lisp lists are not a primitive type; instead singly-linked lists are formed by chaining cons cells together (see Cons Cells). The empty list is represented by the special value ().

Function: listp arg

This functions returns true when its argument, arg, is a list (i.e. either a cons cell or ()).

Function: null arg

Returns a true value if arg is the empty list.