There's a function for that!
kibit is a static code analyzer for Clojure, ClojureScript, cljx
and other Clojure variants. It uses
to search for patterns of code that could be rewritten with a more idiomatic function
or macro. For example if kibit finds the code
(if (some test) (some action) nil)
it will suggest using
(when (some test) (some action))
[lein-kibit "0.1.8"] to your
:plugins vector in your
:user profile. Then you can run
$ lein kibit
to analyze a Leiningen project's namespaces. Kibit will automatically pick up source paths from your project.clj from the following keyseqs:
[:cljsbuild :builds], and
[:cljx :builds]. You can also run Kibit manually on individual files or folders (even if there is no Leiningen
project.clj) by running:
$ lein kibit path/to/some/file.clj #or $ lein kibit path/to/src/ #or $ lein kibit path/to/src/clj/ path/to/src/cljs/util.cljs some/combo/of/files/and/folders.cljx
If you want to know how the Kibit rule system works there are some slides available at http://jonase.github.io/kibit-demo/.
lein kibit returns any suggestions to forms then its exit code will be 1. Otherwise it will exit 0. This can be useful to add in a build step for automated testing.
$ lein kibit ... suggestions follow $ echo $? 1
Automatically rerunning when files change
You can use lein-auto to run kibit automatically when files change. Visit lein-auto's README for installation instructions. Note that this will run kibit over all of your files, not just the ones that have changed.
$ lein auto kibit auto> Files changed: project.clj, [...] auto> Running: lein kibit ... suggestions follow auto> Failed. auto> Files changed: test/my/test/misc.clj auto> Running: lein kibit ... suggestions follow auto> Failed.
Automatically replacing suggestions in source file
You can have kibit automatically apply suggestions to your source files.
Given a file:
(ns example) (+ 1 a)
$ lein kibit --replace
will rewrite the file as:
(ns example) (inc a)
Replacement can also be run interactively:
$ lein kibit --replace --interactive Would you like to replace (+ 1 a) with (inc a) in example.clj:3? [yes/no]
Kibit comes with two reporters, the default plaintext reporter, and a GitHub Flavoured Markdown reporter. To specify a reporter, use the
--reporter commandline argument. For example:
lein kibit --reporter markdown ---- ##### `test/project/core.clj:31` Consider using: ```clojure (when true (println "hi")) ``` instead of: ```clojure (if true (do (println "hi"))) ``` ---- ##### `test/project/core.clj:32` Consider using: ```clojure (println "hi") ``` instead of: ```clojure (do (println "hi")) ```
which renders to:
(when true (println "hi"))
(if true (do (println "hi")))
Usage from inside Emacs
If you use Emacs for hacking Clojure, here's a way to use kibit from
inside Emacs with all the fanciness you are used to from
The kibit-helper package
available from MELPA provides several handy
commands. First, make sure you have MELPA available as a source of
packages (which you may well already have done). As described in their
Getting started section, put the
following into your
(add-to-list 'package-archives '("melpa-stable" . "http://stable.melpa.org/packages/") t)
(If you want to be more on the cutting edge, you can include unreleased versions of packages using the non-stable URL, as explained in the MELPA instructions, but kibit-helper is also available from the less exciting stable repository.)
This will give you three new commands,
M-x kibit M-x kibit-current-file M-x kibit-accept-proposed-change
The first two cause the properly highlighted and hyperlinked kibit output to be
presented in a
*Kibit Suggestions* buffer. The third lets you automatically
apply most of those suggestions to your source. (Suggestions which cite large
blocks of code including comments cannot be automatically applied, as Kibit
discards comments during processing.)
You will likely want to bind the last function to C-x
C-` so it is easy to alternate with the
function (conventionally C-x `) as you walk
through the suggestions made by Kibit:
(global-set-key (kbd "C-x C-`") 'kibit-accept-proposed-change)
Usage from inside vim (through Leiningen plugin)
kibit-vim allows you to analyze the current opened file by running:
Usage from inside vim (with vim-fireplace)
vim-kibit is invoked by running:
source code without any macro expansion or evaluation. A macro can
therefore easily invalidate a rule. Also, kibit will not know if the
+ in the form
(+ x 1) actually refers to a local or to a
function in a namespace other than
some false positives.
It is very easy to write new patterns for
kibit. Take a look at
to see how new patterns are created. If you know of a recurring
pattern of code that can be simplified, please consider sending me a
Bugs can be reported using the GitHub issue tracker.
Thanks to all who have contributed to kibit!
- Leiningen project.clj setting for rule exclusion
- Leiningen project.clj setting for a directory of rules to include
Copyright © 2012 Jonas Enlund
Distributed under the Eclipse Public License, the same as Clojure.