clj-new

Generate new projects from Leiningen or Boot templates, or clj-template projects, using just the clj command-line installation of Clojure!

For support, help, general questions, use the #clj-new channel on the Clojurians Slack.

Getting Started

Note: these instructions assume you are using the Clojure CLI version 1.10.1.727 or later!

The easiest way to use clj-new is by adding an alias to your ~/.clojure/deps.edn file (or ~/.config/clojure/deps.edn file) like this:

    {:aliases
     {:new {:extra-deps {seancorfield/clj-new
                         {:mvn/version "1.1.243"}}
            :exec-fn clj-new/create
            :exec-args {:template "app"}}}
     ...}

Now you can create a basic application:

    clojure -X:new :name myname/myapp
    cd myapp
    clojure -M -m myname.myapp

Run the tests:

    clojure -M:test:runner

or you can create a basic library:

    clojure -X:new :template lib :name myname/mylib
    cd mylib

Run the tests:

    clojure -M:test:runner

If you think you are going to be creating more libraries than applications, you could specify :template "lib" in the :exec-args hash map, to specify the default. Or you could provide different aliases, such as:

    {:aliases
     {:new-app {:extra-deps {seancorfield/clj-new
                             {:mvn/version "1.1.243"}}
                :exec-fn clj-new/create
                :exec-args {:template "app"}}
      :new-lib {:extra-deps {seancorfield/clj-new
                             {:mvn/version "1.1.243"}}
                :exec-fn clj-new/create
                :exec-args {:template "lib"}}}
     ...}

Now you can use those as follows:

    clojure -X:new-app :name myname/myapp
    clojure -X:new-lib :name myname/mylib

The following :exec-args can be provided for clj-new/create:

• :name -- the name of the project (as a symbol or a string); required; must be a qualified project name or a multi-segment dotted project name
• :template -- the name of the template to use (as a symbol or a string); required
• :args -- an optional vector of string to pass to the template itself as command-line arguments
• :env -- a hash map of additional variable substitutions in templates
• :force -- if true, will force overwrite the target directory if it exists
• :help -- if true, will provide a summary of these options as help
• :output -- specify the project directory to create (the default is to use the project name as the directory)
• :query -- if true, instead of actually looking up the template and generating the project, output an explanation of what clj-new will try to do
• :snapshot -- if true, look for -SNAPSHOT version of the template (not just a release version)
• :verbose -- 1, 2, or 3, indicating the level of debugging in increasing detail
• :version -- use this specific version of the template

Unlike Leiningen, clj-new requires that you use either a qualified name for your project, such as <username>/<project-name> or <org-name>/<project-name>, or a dotted name, such as my.project.

If you are going to publish a library, it will have a group ID and an artifact ID (e.g., seancorfield/clj-new) and the group ID should be something unique to you or your organization -- most people use their GitHub username or their company name (or their domain name in reverse, e.g., com.stuartsierra/component). The qualified name you provide to clj-new is effectively group/artifact. clj-new uses that to create the main namespace: src/group/artifact.clj containing (ns group.artifact ...) -- this ensures that when someone uses your library, it's not going to clash with other code because the first portion of the namespace is, again, something unique to you or your organization.

It's good practice to follow this convention even if you are creating an application, or a library that you don't plan to publish, because it will mean that your code is much less likely to clash with any libraries your code uses.

lein new myapp will treat myapp as both the group ID and the artifact ID, which is why a lot of older Clojure libs just have an unqualified lib name, like ring -- but really it's ring/ring and recent versions of the Clojure CLI display a deprecation warning on just ring: see the Deprecated unqualified lib names section near the end of this Inside Clojure post about the -X option. Leiningen also stuck .core onto your project name to create the main namespace, which is why a lot of older Clojure libs have a something.core namespace: just because Leiningen did that by default. Both default behaviors here are bad because they're likely to lead to conflicts with other libraries.

If you really want Leiningen's default behavior -- because you can't think of a better name for your project's main namespace! -- of adding .core to a single segment name such as foo, that can be achieved with clj -X:new :template lib :name foo.core. That will create a folder called foo.core and the project will have a group ID of foo.core and an artifact ID of foo.core -- which is the same behavior as running lein new foo.core (lein new foo creates a folder called foo and the project has a group ID of foo and an artifact ID of foo, even though the main namespace will be foo.core).

Templates

Built-in templates are:

• app -- A minimal Hello World! application with deps.edn. Can run it via clj -M -m and can test it with clj -M:test:runner.
• lib -- A minimal library with deps.edn. Can test it with clj -M:test:runner.
• template -- A minimal clj-new template.

Note: you can find third-party templates on Clojars using these searches <template-name>/clj-template, <template-name>/lein-template or <template-name>/boot-template.

The project name should be a qualified Clojure symbol, where the first part is typically your GitHub account name or your organization's domain reversed, e.g., com.acme, and the second part is the "local" name for your project (and is used as the name of the folder in which the project is created), e.g., com.acme/my-cool-project. This will create a folder called my-cool-project and the main namespace for the new project will be com.acme.my-cool-project, so the file will be src/com/acme/my_cool_project.clj. In the generated pom.xml file, the group ID will be com.acme and the artifact ID will be my-cool-project -- following this pattern means you are already set up for publishing to Clojars (or some other Maven-like repository).

An alternative is to use a multi-segment project name, such as com.acme.another-project. This will create a folder called com.acme.another-project (compared to above, which just uses the portion after the /). The main namespace will be com.acme.another-project in src/com/acme/another_project.clj, similar to the qualified project name above. In the generated pom.xml file, the group ID will be the "stem" of the project name (com.acme) and the artifact ID will be the full project name (com.acme.another-project) -- again, you'll be set up for publishing to Clojars etc, but be aware of the difference between how dotted names and qualified names affect the generated project.

You can, of course, modify the generated pom.xml file to have whatever group and artifact ID you want, if you don't like these defaults.

The app Template

The generated project is an application. It has a -main function in the main project namespace, with a (:gen-class) class in the ns form. In addition to being able to run the project directly (with clojure -M -m myname.myapp) and run the tests, you can also build an uberjar for the project with clojure -X:uberjar, which you can then run with java -jar myapp.

The generated project includes a pom.xml file purely for "good hygiene". It will be kept in sync with deps.edn automatically whenever you run clojure -X:uberjar to build the application and it will be added to the JAR file, along with a generated pom.properties file. If you delete pom.xml, you will also need to remove :sync-pom true from the :exec-args for depstar in the deps.edn file.

The lib Template

The generated project is a library. It has no -main function. In addition to being able to run the tests, you can also build a jar file for deployment with clojure -X:jar. You will probably need to adjust some of the information inside the generated pom.xml file before deploying the jar file.

The generated project includes a pom.xml file on the assumption that you will be deploying the library to Clojars or a similar repository. It will be kept in sync with deps.edn automatically whenever you run clojure -X:jar to build the library and it will be added to the JAR file, along with a generated pom.properties file. If you do not intend to deploy the library and you want to delete the pom.xml file, you will also need to remove :sync-pom true from the :exec-args for depstar in the deps.edn file.

If you are going to deploy the library, you'll probably want to review and adjust some of the fields in the pom.xml (developer information, group/artifact, version, SCM, licensing etc) -- although the defaults should mostly be suitable out of the box.

Once you've updated the pom.xml file, you can install it locally with clojure -X:install or deploy it to Clojars with clojure -X:deploy. For that you need these environment variables set:

• CLOJARS_USERNAME -- your Clojars username
• CLOJARS_PASSWORD -- your Clojars password

The template Template

The generated project is a very minimal clj-template. It has no -main function and has no tests. You can however build a jar file for deployment with clojure -X:jar. You will probably need to adjust some of the information inside the generated pom.xml file before deploying the jar file.

Note: when you create a template project called myname/mytemplate, you will get a folder called mytemplate and the pom.xml file will specify the group/artifact as mytemplate/clj-template which is the convention expected by clj-new.

As with the lib template, this template includes a pom.xml to make it easier to deploy the template as a library. Once you have reviewed and possibly updated the pom.xml file, you can install it locally or deploy it to Clojars, via the appropriate aliases.

The Generated pom.xml File

Each of the built-in templates produces a project that contains a pom.xml file, which is used to build the uberjar (app) or jar file (lib and template), as well as guide the deployment of the latter two. If you don't plan to deploy the library or template, or you just don't want a pom.xml lying around for your application, you can delete it -- but you will also need to remove :sync-pom true from the :exec-args for depstar in the generated deps.edn file.

The goal is that if you used an appropriate myname/myapp style name for the project that you asked clj-new to create, then most of the fields in the pom.xml file should be usable as-is.

You can override the default value of several fields in the pom.xml file using the :env exec-arg to clj-new/create as a hash map:

• :group -- defaults to the myname portion of myname/myapp,
• :artifact -- defaults to the myapp portion of myname/myapp,
• :version -- defaults to "0.1.0-SNAPSHOT",
• :description -- defaults to "FIXME: my new ..." (application, library, or template),
• :developer -- defaults to a capitalized version of your computer's logged in username.
• :scm-domain -- defaults to github.com; used in all the SCM links in the generated projects: https://{{scm-domain}}/{{group}}/{{artifact}}

The :description field is also used in the generated project's README.md file.

Example:

    clojure -X:new-app :name myname/myapp \
      :env '{:group myusername :artifact my-cool-app :version "1.2.3"}'

This creates the same project structure as in the earlier myname/myapp example except that the generated pom.xml file will contain:

  <groupId>myusername</groupId>
  <artifactId>my-cool-app</artifactId>
  <version>1.2.3</version>
  <description>FIXME: my new application.</description>
  <url>https://github.com/myusername/my-cool-app</url>

Once you have generated the project, running depstar to build the JAR file will keep the pom.xml in sync with the dependencies in your deps.edn file, and you can update the version automatically using depstar's :version exec argument. You can also change the groupId and/or artifactId via depstar's :group-id and/or :artifact-id exec arguments respectively.

The Generated LICENSE File

The generated projects (from the built-in app, lib, and template templates) all contain a LICENSE file which is the Eclipse Public License (version 1.0) and that is also mentioned in the generated README.md files. This is a tradition that started with Leiningen's lein new and carried over into boot new and now clj-new. The idea is that it's better to ensure any open source projects created have a valid license of some sort, as a starting point, and historically most Clojure projects use the EPLv1.0 because Clojure itself and the Contrib libraries have all used this license for a long time.

You are not required to open source your generated project! Just because the projects are generated with an open source LICENSE file and have a License section in their README.md files does not mean you need to keep that license in place.

You are not required to use EPLv1.0 for your project! If you prefer a different license, use it! Replace the LICENSE file and update the README.md file to reflect your personal preference in licensing (I have tended to use the Apache License 2.0 in most of my open source projects, prior to working with Clojure).

Note: if you incorporate any source code from other people's open source projects, be aware of the legal implications and that you must respect whatever license they have used for that code (which may require you to release your enhancements under the same license and will, most likely, require you to include their copyright notices, etc). Do not copy other people's code without attribution!

General Template Usage

The general form of the command is:

clojure -X:new :template template-name :name project-name :args '[arg1 arg2 arg3 ...]'

As noted above, project-name should be a qualified symbol, such as mygithubusername/my-new-project, or a multi-segment symbol, such as my.cool.project. Some templates will not work with the former but it is recommended you try that format first.

If template-name is not one of the built-in ones (or is not already on the classpath), this will look for template-name/clj-template (on Clojars and Maven Central). If it doesn't find a clj template, it will look for template-name/boot-template instead. If it doesn't find a Boot template, it will look for template-name/lein-template instead. clj-new should be able to run any existing Leiningen or Boot templates (if you find one that doesn't work, please tell me about it!). clj-new will then generate a new project folder based on the project-name containing files generated from the specified template-name. It does that by requiring clj.new.<template-name> (or boot.new.<template-name> or leiningen.new.<template-name>) and invoking the <template-name> function inside that namespace, passing in <project-name> and those arguments from the command line.

Alternatively, template-name can be a :git/url and :sha like this:

clj -X:new :template '"https://github.com/somename/someapp@c1fc0cdf5a21565676003dbc597e380467394a89"' \
  :name project-name :args '[arg1 arg2 arg3 ...]'

In this case, clj.new.someapp must exist in the template and clj.new.someapp/someapp will be invoked to generate the template. A GitHub repository may include multiple templates, so you can also use this form:

clj -X:new :template '"https://github.com/somename/somerepo/someapp@c1fc0cdf5a21565676003dbc597e380467394a89"' \
  :name project-name :args '[arg1 arg2 arg3 ...]'

somename/somerepo here contains templates in subdirectories, including someapp. Again, clj.new.someapp must exist in the template in that subdirectory and clj.new.someapp/someapp will be invoked to generate the template.

Or, template-name can be a :local/root and template name like this:

clj -X:new :template '"/path/to/clj-template::new-app"' \
  :name project-name :args '[arg1 arg2 arg3 ...]'

In this case, clj.new.new-app must exist in the template and clj.new.new-app/new-app will be invoked to generate the template.

Note: since the :git/url and :local/root forms of :template cannot be provided as Clojure symbols, they must be provided as Clojure strings, with "...", and those must be quoted for the shell correctly, with '...' around the string.

If the folder for project-name already exists, clj-new will not overwrite it unless you specify the :force option.

Example Usage

Here are some examples, generating projects from existing templates:

    clojure -X:new :template luminus :name yourname/example.webapp \
      :output '"mywebapp"' :args '["+http-kit" "+h2" "+reagent" "+auth"]'

This creates a folder called mywebapp with a Luminus web application that will use http-kit, the H2 database, the Reagent ClojureScript library, and the Buddy library for authentication. The -main function is in yourname.example.webapp.core, which is in the mywebapp/src/clj/yourname/example/webapp/core.clj file. Note that the Luminus template produces a Leiningen-based project, not a CLI/deps.edn one, but you can also tell it to produce a Boot-based project (with +boot).

    clojure -X:new :template re-frame :name yourname/spa \
      :output '"front-end"' :args '["+garden" "+10x" "+routes"]'

This creates a folder called front-end with a ClojureScript Single Page Application that uses Garden for CSS, re-frame-10x for debugging, and Secretary for routing. The entry point is in the yourname.spa.core namespace which is in the front-end/src/cljs/yourname/spa/core.cljs file. As with Luminus, the re-frame template produces a Leiningen-based project, not a CLI/deps.edn one.

    clojure -X:new :template electron-app :name yourname/example

This creates a folder called example with a skeleton Electron application, using Figwheel and Reagent. The entry point is in the example.main.core namespace which is in the example/src/main/example/main/core.cljs file. This Electron template produces a CLI/deps.edn-based project.

clj Templates

clj templates are very similar to Leiningen and Boot templates but have an artifact name based on clj-template instead of lein-template or boot-template and use clj instead of leiningen or boot in all the namespace names. In particular the clj.new.templates namespace provides functions such as renderer and ->files that are the equivalent of the ones found in leiningen.new.templates when writing a Leiningen Template (or boot.new.templates when writing a Boot Template). The built-in templates are clj templates, that produce clj projects with deps.edn files.

If your template name is foo-bar, then you should have clj.new.foo-bar as the main namespace and it should contain a foo-bar function that will render the template:

;; src/clj/new/foo_bar.clj:
(ns clj.new.foo-bar ,,,)

(defn foo-bar
  "Generate a cool new foo bar project!"
  [name & args]
  ,,,)

When you publish it to Clojars, it should have a group ID matching the template name and an artifact ID of clj-template: foo-bar/clj-template. If you expect people to depend on the template via GitHub, you should also name the repo foo-bar so that https://github.com/<username>/foo-bar is the :git/url people will use.

A minimal example, using the default bare bones template:

$ clojure -X:new :template template :name myname/mytemplate
Generating a project called mytemplate that is a 'clj-new' template

You will now have a folder called mytemplate that is a very minimal template.

To create a new project based on that template, you need to have it on the classpath (just as if it were a library) and you also need clj-new on the classpath since you are using it to generate a project from that template:

$ clojure -Sdeps '{:deps {myname/mytemplate {:local/root "mytemplate"}}}' \
  -X:new :template mytemplate :name myname/myproject
Generating fresh 'clj new' mytemplate project.
$ tree myproject
myproject
|____deps.edn
|____src
| |____myname
| | |____myproject
| | | |____foo.clj

This example uses a local template project structure, which is probably a good idea when you are developing your template, because the only real way to test a template is by trying to use it to generate a new project.

Once you have it working, you can publish it to GitHub or Clojars just like a regular library.

Arguments

Previous sections have revealed that it is possible to pass arguments to templates. For example:

    clojure -X:new :template custom-template :name project-name \
      :args '[arg1 arg2 arg3]'

These arguments are accessible in the custom-template function as a second argument.

(ns clj.new.custom-template ,,,)

(defn custom-template
  [name & args]
  (println name " has the following arguments: " args))

Nearly all templates will expect these to be strings so you will need to quote them in the :args vector:

    clojure -X:new :template custom-template :name project-name \
      :args '["arg1" "arg2" "arg3"]'

clj Generators

Whereas clj templates will generate an entire new project in a new directory, clj generators are intended to add / modify code in an existing project.

You can either say clojure -X:new clj-new/generate ... or add an alias for it:

    {:aliases
     {:generate {:extra-deps {seancorfield/clj-new
                              {:mvn/version "1.1.243"}}
                 :exec-fn clj-new/generate}}
     ...}

Given the alias above, you can say clojure -X:generate to run one or more generators, based on a :generate vector argument that you provide. Each generator in the vector is a string -- either "type" or "type=name". The type specifies the type of generator to use. The name is the main argument that is passed to the generator.

A clj generator can be part of a project or a template. A generator foo, has a clj.generate.foo/generate function that accepts at least two arguments, prefix and the name specified as the main argument. prefix specifies the directory in which to perform the code generation and defaults to src (it cannot currently be overridden). In addition, any additional arguments are passed as additional arguments to the generator.

There are currently a few built-in generators:

• file
• ns
• def
• defn
• edn

The file generator creates files relative to the prefix. It optionally accepts a body, and file extension, supplied via an :args vector of strings. Those default to nil and "clj" respectively.

# Inside project folder, relying on the clj-new dependency.
clojure -X:generate :generate '["file=foo.bar"]' :args '["(ns foo.bar)" "clj"]'

The ns generator creates a clojure namespace by using the file generator and providing a few defaults.

clojure -X:generate :generate '["ns=foo.bar"]'

This will generate src/foo/bar.clj containing (ns foo.bar) (and a placeholder docstring). It will not replace an existing file.

clojure -X:generate :generate '["defn=foo.bar/my-func"]'

If src/foo/bar.clj does not exist, it will be generated as a namespace first (using the ns generator above), then a definition for my-func will be appended to that file (with a placeholder docstring and a dummy argument vector of [args]). The generator does not check whether that defn already exists so it always appends a new defn.

Both the def and defn generators create files using the ns generator above.

The edn generator uses the file generator internally, with a default extension of "edn".

clojure -X:generate :generate '["edn=foo.bar"]' :args '["(ns foo.bar)"]'

You can provide as many generators as you want in the :generate vector, but if you provide an :args vector then those arguments will be passed into each of the generator functions, so you may still need to run multiple clojure -X:generate commands.

The exec-args available for the generate function are:

• :generate -- a (non-empty) vector of generator strings to use
• :args -- an optional vector of string to pass to the generator itself as command-line arguments
• :force -- if true, will force overwrite the target directory/file if it exists
• :help -- if true, will provide a summary of these options as help
• :prefix -- specify the project directory in which to run the generator (the default is src but :p '"."' will allow a generator to modify files in the root of your project)
• :snapshot -- if true, look for -SNAPSHOT version of the template (not just a release version)
• :template -- load this template (using the same rules as for clj-new/create above) and then run the specified generator
• :version -- use this specific version of the template

Releases

This project follows the version scheme MAJOR.MINOR.COMMITS where MAJOR and MINOR provide some relative indication of the size of the change, but do not follow semantic versioning. In general, all changes endeavor to be non-breaking (by moving to new names rather than by breaking existing names). COMMITS is an ever-increasing counter of commits since the beginning of this repository.

Latest stable release: 1.1.243

Roadmap

• Improve the built-in template template so that it can be used to seed a new clj project.

License

Copyright © 2016-2021 Sean Corfield and the Leiningen Team for much of the code -- thank you!

Distributed under the Eclipse Public License version 1.0.