Common Lisp the Language is a book by GuySteele about CommonLisp. It pre-dates the ANSI Common Lisp specification (see the CommonLispHyperspec) but being in textbook style it’s much more useful for beginners than a formal specification.

The second edition of the book is available online in electronic form:

On a Debian system the package cltl will download a local copy of the HTML.

The following two Emacs packages let you lookup functions and variables.


cltl2.el by UtzUweHaus provides a simple cltl2-lookup for opening your web browser (the usual browse-url) at the page for a function or variable. The package is included as an extra in the ILispMode distribution.

By default cltl2.el uses the online copy at CMU, but cltl2-root-url can be set to a different location, including a local downloaded copy.


browse-cltl2.el by HolgerSchauer does the same sort of thing, using browse-url to goto a function, or to go to the book’s index. Some ILispMode hooks are included. The package can be obtained from the author at

The default is to look for a local copy under /usr/doc/html/cltl but that can be customized or an online copy used.

For current Emacs (both GnuEmacs and XEmacs) the call (make-hash-table 0) needs to be changed to just (make-hash-table).