Common Lisp may have more libraries than you think. See:

Quicklisp is the de-facto package manager, but not the only tool.

Some terminology first

  • In the Common Lisp world, a package is a way of grouping symbols together and of providing encapsulation. It is similar to a C++ namespace, a Python module or a Java package.

  • A system is a collection of CL source files bundled with an .asd file which tells how to compile and load them. There is often a one-to-one relationship between systems and packages, but this is in no way mandatory. A system may declare a dependency on other systems. Systems are managed by ASDF (Another System Definition Facility), which offers functionalities similar to those of make and, and has become a de facto standard.

  • A Common Lisp library or project typically consists of one or several ASDF systems (and is distributed as one Quicklisp project).

Install Quicklisp

Quicklisp is more than a package manager, it is also a central repository (a dist) that ensures that all libraries build together. This involves some manual work (like reporting errors to package authors), so this is why Quicklisp releases its dist updates once a month (but fear not, we have other tools).

It provides its own dist but it is also possible to build our own.

To install it, we can either:

1- run this command, anywhere:

curl -O

and enter a Lisp REPL and load this file:

sbcl --load quicklisp.lisp


2- install the Debian package:

apt-get install cl-quicklisp

and load it, from a REPL:

(load "/usr/share/cl-quicklisp/quicklisp.lisp")

Then, in both cases, still from the REPL:


This will create the ~/quicklisp/ directory, where Quicklisp will maintain its state and downloaded projects.

If you want Quicklisp to always be loaded in your Lisp sessions, run (ql:add-to-init-file): this adds the right stuff to the init file of your CL implementation. Otherwise, you have to run (load "~/quicklisp/setup.lisp") in every session if you want to use Quicklisp or any of the libraries installed through it.

It adds the following in your (for example) ~/.sbclrc:

  (let ((quicklisp-init (merge-pathnames "quicklisp/setup.lisp"
    (when (probe-file quicklisp-init)
      (load quicklisp-init)))

Install libraries

In the REPL:

(ql:quickload "package-name")

and voilà. See Quicklisp’s documentation for more commands.

Note also that dozens of Common Lisp libraries are packaged in Debian. The package names usually begin with the cl- prefix (use apt-cache search --names-only "^cl-.*" to list them all).

For example, in order to use the CL-PPCRE library (for regular expressions), one should first install the cl-ppcre package.

Then, in SBCL and ECL, it can be used with:

(require "asdf")
(require "cl-ppcre")
(cl-ppcre:regex-replace "fo+" "foo bar" "frob")

See more:

Advanced dependencies management

Quicklisp installs the libraries into ~/quicklisp/local-projects/. A library installed here is automatically available for every project.

Providing our own version of a library. Cloning projects.

Given the property above, we can clone any library into the local-projects directory and it will be found by quicklisp and available right-away:

(ql:quickload "package")

And also given the M-. “go to this symbol definition” feature in Slime (and M-, to go back), it’s really easy to not only explore but start tweaking and extending other libraries.

How to work with local versions of libraries

If we need libraries to be installed locally, for only one project, or in order to easily ship a list of dependencies with an application, we can use Qlot. This is like Python’s virtual environments.

Quicklisp also provides Quicklisp bundles. They are self-contained sets of systems that are exported from Quicklisp and loadable without involving Quicklisp.

At last, there’s Quicklisp controller to help us build dists. Some projects use this, like CL21.

Read more

See also

  • Qi - a package manager for Common Lisp