CDS: A Clojure Documentation Site

An assorted collection of tutorials, guides, and other documentation (by various authors) for the Clojure programming language and its ecosystem. Read the guides online.

CDS (Clojure Documentation Site) is a community documentation project for the Clojure programming language, and is developed on GitHub.

Pull Requests should be made against the source branch, with changes to the Markdown files. The HTML on the main branch is auto-generated using Cryogen.

Rationale & History

The rationale is explained in more detail in the announcement blog post.

CDS was started in early October, 2012, by several active members of the Clojure community due to their dissatisfaction at the time with the state of documentation and the documentation contribution process (that involved mailing the Clojure Contributor Agreement in paper).

Unfortunately, access to the original infrastructure hosting, was lost several years ago. This current incarnation is a reboot of that site using Cryogen and hosted as a GitHub organization website.

Since the original creation of CDS in 2012, the website has improved and expanded dramatically, and now includes a number of tutorials as well as extensive community resources. In addition, the contribution process has been simplified: the Contributor Agreement can be e-signed and the clojure-site repo accepts Pull Requests. As a result of that, CDS contained content that was essentially duplicated on and was not as well-maintained as so that content is being removed from CDS.

Funding for extensive work on CDS in 2023 is generously provided by Clojurists Together as part of their Long-Term Funding for Sean Corfield.


The goal is to produce quality technical documentation for Clojure users and potential adopters with various expertise levels.

CDS strives to cover all aspects of Clojure: from tutorials and language guides to overview of the ecosystem, how libraries are developed and published, topics operations engineers will be interested in, JVM ecosystem tools and so on.

CDS also strives to avoid duplicating content from the official Clojure site but will link extensively to that, in order to make that content easier to find and navigate.

Adopting a language always takes more than just reading a book or a few tutorials about language features. Understanding design goals, the ecosystem and operations is just as important. CDS will try to address this.

What CDS is Not

What's not here:

CDS needs a lot of work and redesign (as in, the way it works) which will take a while. CDS is not concerned with providing the API reference; only tutorials, guides, and linking to other relevant resources.


CDS is structured as a number of guides. They broadly fall into 4 categories:


The Tutorials are intended for complete newcomers and should include a lot of hand holding. They don't assume any previous familiarity with Clojure, the JVM, the JVM tool ecosystem, functional programming, immutability, and so on.

Target audience: newcomers to the language.

Language guides

The Language Guides are more in-depth, focused on various aspects of the language and interoperability. Examples of such guides include:

  • Collections & Sequences
  • Concurrency & Parallelism
  • Interoperability
  • Laziness
  • Macros

Target audience: from developers who already have some familiarity with the language to those who have been using it for a while.

Tools & Ecosystem guides

These guides cover key Clojure ecosystem tools such as Leiningen, Clojars, nREPL, Emacs, vim, Calva, etc. It also covers important ecosystem projects that are not tools: books, communities, etc.

Target audience: all developers using or interested in the Clojure programming language.


Concise Clojure example code, categorized by subject.

How To Contribute

First of all: you can contribute to Clojure documentation even if you have 15 minutes to spare a day.

No contribution is too small: feel free to suggest grammar improvements, better code examples, submit pull requests with just one new paragraph or even a couple of spelling corrections. Editing and proof-reading is also a great way to contribute.

If you found a mistake you'd like to report and do not want to make edits and go through the pull request process, please post your findings in one of the following places:

Thank you!


This site is built with Cryogen and hosted as a GitHub organization website.

Clone the repository, checkout the source branch, and run clojure -M:build to generate the public folder containing the rendered HTML version of the site (which is actually the main branch of the repository, so that it is published to automatically).

You can view the generated version with clojure -X:serve which should open a browser to port 3000 (of localhost). This will automatically regenerate the public folder as files are changed in content etc.

See for instructions about including interactive code snippets in an article.

Contributing To Existing Guides

First, pick a topic that sounds interesting. Writing documentation takes some effort and working on something that is interesting to you will motivate you. Next, find the article you want to contribute to under ./content/md/articles/. It is a Markdown file with inline code snippets.

At the top of each article you will usually find what it is supposed to cover. Please stick to that list.

Then fork the repository, create a topic branch, and start writing.

When writing, periodically view results in the browser (see clojure -X:serve described above for running a local server) and make sure code examples are rendered correctly and that there are no serious formatting issues. If you are not a Markdown or CSS guru, it's OK, but submitting changes that seriously break formatting and force maintainers to work on fixing them is not very productive (or nice).

After making the changes you want, run them by a fellow developer, edit them a couple of times and submit a pull request on GitHub. Please be patient. It may take a while for CDS maintainers to get to your pull request, read your changes, and suggest improvements.

Don't get discouraged if asked to make more edits or even completely rewrite some parts from scratch. All good documentation out there is a result of dozens of edits, corrections, and sometimes ground-up rewrites. This is normal. We want Clojure documentation to be high quality just like the language and clojure.core.

For some guidance on writing great documentation, see

Contributing New Guides

If you feel there may be a guide missing, please run your idea by other CDS contributors in one of these places:

What You Must Not Do

Please respect copyright of other Clojure-related content out there. You must not copy content from, books on Clojure, blogs and other sources unless you are the primary author of them and understand the implications.

Contributors Policy

If you are the primary author of a substantial document, you are encouraged to include your name in a ## Contributors section near the end of it, noting that you are the original author. If you have made substantial contributions to an existing document, you might add your name to the ## Contributors section.

If you have at least one non-trivial (e.g. not just typo fixes) pull request merged, you can ask to be added to the repository as a collaborator. We still encourage contributors to use pull requests for content review and discussions for new content, but you will be able to push small improvements directly.


All the content is distributed under the CC BY 3.0 license and are copyright their respective primary author(s).