Editing Common Lisp (section)

===Other types===
Other data types in Common Lisp include:

*''Pathnames'' represent files and directories in the [[filesystem]]. The Common Lisp pathname facility is more general than most operating systems' file naming conventions, making Lisp programs' access to files broadly portable across diverse systems.
*Input and output ''streams'' represent sources and sinks of binary or textual data, such as the terminal or open files.
*Common Lisp has a built-in [[pseudo-random number generator]] (PRNG). ''Random state'' objects represent reusable sources of pseudo-random numbers, allowing the user to seed the PRNG or cause it to replay a sequence.
*''Conditions'' are a type used to represent errors, exceptions, and other "interesting" events to which a program may respond.
*''Classes'' are [[first-class object]]s, and are themselves instances of classes called [[metaclasses|metaobject classes]] ([[metaclasses]] for short).
*''Readtables'' are a type of object which control how Common Lisp's reader parses the text of source code.  By controlling which readtable is in use when code is read in, the programmer can change or extend the language's syntax.