Practical Common Lisp

CHAPTER 11Collections

Like most programming languages, Common Lisp provides standard data types that collect multiple values into a single object. Every language slices up the collection problem a little bit differently, but the basic collection types usually boil down to an integer-indexed array type and a table type that can be used to map more or less arbitrary keys to values. The former are variously called arrays, lists, or tuples; the latter go by the names hash tables, associative arrays, maps, and dictionaries.

Lisp is, of course, famous for its list data structure, and most Lisp books, following the ontogeny-recapitulates-phylogeny principle of language instruction, start their discussion of Lisp's collections with lists. However, that ...