Leiningen is the most widely-contributed-to Clojure project a the time of this writing. We welcome potential contributors and do our best to try to make it easy to help out.
Discussion occurs primarily in the #leiningen channel on Libera chat.
Please report issues on the issue tracker. Issues used to be reported in the GitHub tracker so you may want to check there to see if things have already been reported.
Code submissions should be sent as pull
requests. Please
use topic branches when sending pull requests rather than committing
directly to main
in order to minimize unnecessary merge commit
clutter. Direct pull requests towards the main
branch, not the
stable branch.
Note: the canonical repository for Leiningen is on Codeberg but we maintain a mirror on GitHub for the time being in order to ease the transition. Please update your links and git remotes.
The definitions of the various tasks reside in src/leiningen
in the
top-level project. The underlying mechanisms for things like
project.clj
parsing, classpath calculation, and subprocess launching
are implemented inside the leiningen-core
subproject.
See the
readme for the leiningen-core library
and doc/PLUGINS.md
for more details on how Leiningen's codebase is
structured.
Try to be aware of the conventions in the existing code, except the
one where we don't write tests. Make a reasonable attempt to avoid
lines longer than 80 columns or function bodies longer than 20
lines. Don't use when
unless it's for side-effects. Don't introduce
new protocols. Use ^:internal
metadata to mark vars which can't be
private but shouldn't be considered part of the public API.
You don't need to "build" Leiningen per se, but when you're developing on a checkout you will need to get its dependencies in place and compile some of the tasks. Assuming you are in Leiningen's project root, you can do that like this:
$ cd leiningen-core
$ lein bootstrap # or lein.bat on Windows.
The lein
command is a stable release of Leiningen on your $PATH
– preferably
the newest one. If you don't have a stable lein
installed, simply check out
the stable
branch and copy bin/lein
to somewhere on your $PATH
, then
switch your branch back.
If you want to use your development copy for everyday usage, symlink
bin/lein
to somewhere on your $PATH
. You'll want to rename your
stable installation to keep them from interfering; typically you can
name that lein2
or lein-stable
.
When dependencies in Leiningen change, you may have to do rm .lein-classpath
in the project root, though in most cases this will be done automatically. If
dependencies in leiningen-core change, you have to redo the lein bootstrap
step mentioned earlier.
Using bin/lein
alone from the main branch without a full checkout
is not supported. If you want to just grab a shell script to work
with, use the stable
branch.
Since a development version is not uberjared, it can be rather slow compared to a stable release. If this is annoying and you depend on a recent fix or enhancement, you can build an uberjar from main as follows:
# NB! You have to use *bin*/lein to build the uberjar
$ bin/lein uberjar
# ^ Last line printed from this command will tell the location of the standalone
$ cp target/leiningen-2.5.2-SNAPSHOT-standalone.jar $HOME/.lein/self-installs
$ cp bin/lein $HOME/bin/lein-main
Here, 2.5.2-SNAPSHOT is the version we've built, and we have $HOME/bin
on our
$PATH.
Note that changes on main won't be visible in the uberjared version unless you overwrite both the lein script and a freshly created uberjar.
Before you submit a pull request, we would be very happy if you ensure that the changes you've done doesn't break any of the existing test cases. While there is a test suite, it's not terribly thorough, so don't put too much trust in it. Patches which add test coverage for the functionality they change are especially welcome.
To run the test cases, run bin/lein test
in the root directory: This will test
both leiningen-core
and leiningen
itself. Do not attempt to run the tests
with a stable version of Leiningen, as the namespaces conflict and you may end
up with errors during the test run.