The Common Lisp package is organized into four main files:
This is the main file, which contains basic functions and information about the package.
cl-lib.el includes all necessary autoload commands for the
functions and macros in the other three files. All you have to do is
(require 'cl-lib), and
cl-lib.el will take care of pulling in the other
files when they are needed.
This file contains the larger, more complex or unusual functions. It is kept separate so that packages which only want to use Common Lisp fundamentals like the cl-incf function won’t need to pay the overhead of loading the more advanced functions.
This file contains most of the advanced functions for operating on sequences or lists, such as cl-delete-if and cl-assoc.
This file contains the features that are macros instead of functions. Macros expand when the caller is compiled, not when it is run, so the macros generally only need to be present when the byte-compiler is running (or when the macros are used in uncompiled code). Most of the macros of this package are isolated in cl-macs.el so that they won’t take up memory unless you are compiling.
There is another file,
cl.el, which was the main entry point to
this package prior to Emacs 24.3. Nowadays, it is replaced by
The two provide the same features (in most cases), but use different function
names (in fact, cl.el mainly just defines aliases to the cl-lib.el
Since the old
cl.el does not use a clean namespace, Emacs has a policy that
packages distributed with Emacs must not load
cl at run time. (It is ok for
them to load
cl at compile time, with
eval-when-compile, and use the
macros it provides.) There is no such restriction on the use of
code should use
cl-lib rather than
There is one more file,
cl-compat.el, which defines some
routines from the older Quiroz
cl.el package that are not otherwise present
in the new package. This file is obsolete and should not be used in new code.