5.6.1 Apropos

Common Lisp defines 978 symbols. There are probably hundreds of others as well for language extensions, libraries, a graphical user interface, etc. You will not remember all of the names, but you will probably remember parts of them. Once you have a good guess at a part of the name, you can find all of the matching names by using a tool called APROPOS.

$ sbcl
* (apropos "MAP" :cl)
MAP (fbound)
MAP-INTO (fbound)
MAPC (fbound)
MAPCAN (fbound)
MAPCAR (fbound)
MAPCON (fbound)
MAPHASH (fbound)
MAPL (fbound)
MAPLIST (fbound)

$ clisp
[1]> (apropos "MAP" :cl)
MAP                                        function
MAP-DEPENDENTS                             function
MAP-INTO                                   function
MAPC                                       function
MAPCAN                                     function
MAPCAR                                     function
MAPCON                                     function
MAPHASH                                    function
MAPL                                       function
MAPLIST                                    function

APROPOS expects a string or a symbol — this provides the fragment of the name that you’d like to find. An optional second argument designates a package; use it if you’d like to limit your search to the symbols in a particular package. The package designator can be a string or symbol matching the name or nickname of a package or it can be the package object itself. If you omit the package designator, then APROPOS will search for symbols in all packages.