Introduction — Why Cask?

Cask is an Emacs Lisp project management tool, similar to Maven or Leiningen. It aims to control and automate the entire life cycle of an Emacs Lisp package, including dependency management, packaging, distribution and testing.

This document provides a motivation for using Cask in your Emacs Lisp packages, or in your personal Emacs configuration.

Package development

So, why should your Emacs Lisp project use Cask? Do you know why:

  • Ruby projects have a gemspec file?
  • Node.js projects have a package.json file?
  • Clojure projects have a project.clj file?
  • Emacs Lisp projects have a Cask file?

Actually, let us rephrase the last statement.

  • Some Emacs Lisp projects have a Cask file?

No, let’s try that again.

  • Some Emacs Lisp projects do not have a Cask file?

We will argue that some Emacs Lisp projects may not benefit directly from using Cask. Those are the projects that:

  • Do not have any dependencies
  • Do not have any tests
  • Do not care about consistency
  • Do not care about compiler warnings
  • Do not want to make it easy for contributors

So all in all, projects that are not worth using.

Emacs package development has improved drastically during the last couple of years. From single Emacs Lisp files uploaded to the Emacs Wiki, to high quality packages, using VCS, that are tested, installable via a package manager and more.

But there’s one thing still missing and that is consistency. Note that every Ruby project has a gemspec file, every Node.js project has a package.json file and every Clojure project has a project.clj file.

In those environments, projects are structured, tested, packaged, compiled, released in the same way. If you find a new project and want to find out what dependencies it has, you will know exactly where to look. If you want to find the test for a specific feature, you know exactly where to look.

For Emacs Lisp projects using Cask, this is true as well.

So, even if you feel that your Emacs Lisp project does not have direct benefit of using Cask, please do so any way. If not for you, do it for other Emacs Lisp developers.

Emacs configuration

If you look at the majority of Emacs configurations out there, you will see a few different types setups. These are the major ones:

Using package.el directly

It usually looks something like this:

(require 'package)
 (lambda (package)
   (unless (package-installed-p package)
     (package-install package)))
 '(s f dash flycheck prodigy ...))

I did something like this in my configuration once as well, but I no longer have to, because Cask exists.


I have over 60 packages in my Emacs configuration. Can you imagine how much work it would require to keep all of those up to date?

Bundled packages

This has the same “keeping up to date” issue as the submodules approach. But it’s even worse. Storing dependencies as part of the repository is madness. I shouldn’t have to explain why.


This is obviously what we want. All it is, is a single file that declares a list of dependencies. You know where to look if you want to find out what dependencies a configuration has and it’s easy to keep packages up to date.