kibit

There's a function for that!

kibit is a static code analyzer for Clojure which uses core.logic to search for patterns of code for which there might exist a more idiomatic function or macro. For example if kibit finds the code

(if (some test)
  (some action)
  nil)

it will make the suggestion to use the when macro instead of if.

Usage

Add [lein-kibit "0.0.7"] to your :plugins vector in your :user profile (Leiningen 2) or if you are using Leiningen 1:

$ lein plugin install lein-kibit 0.0.7

Then you can run

$ lein kibit

to analyze your namespaces. You can analyze individual files by running

$ lein kibit path/to/some/file.clj

Usage from inside Emacs

If you use Emacs for hacking Clojure, here's a way to use kibit from inside Emacs with all the fancyness you are used from M-x compile. Put the following into your ~/.emacs:

;; Teach compile the syntax of the kibit output
(require 'compile)
(add-to-list 'compilation-error-regexp-alist-alist
	     '(kibit "At \\([^:]+\\):\\([[:digit:]]+\\):" 1 2 nil 0))
(add-to-list 'compilation-error-regexp-alist 'kibit)

;; A convenient command to run "lein kibit" in the project to which
;; the current emacs buffer belongs to.
(defun kibit ()
  "Run kibit on the current project.
Display the results in a hyperlinked *compilation* buffer."
  (interactive)
  (compile "lein kibit"))

This will give you a new command M-x kibit RET, and the properly highlighted and hyperlinked kibit output is presented in a *compilation* buffer.

Known limitations

Kibit reads source code without any macro expansion or evaluation. A macro can therefor easily invalidate a rule. Also, kibit will not know if the symbol + in the form (+ x 1) actually refers to a local or to a function in a namespace other than clojure.core. Expect some false positives.

Contributing

It is very easy to write new patterns for kibit. Take a look at control-structures.clj 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 pull request.

Bugs can be reported using the github bug tracker.

Contributors

• Jonas Enlund
• Phil Hagelberg
• Tassilo Horn
• Alan Malloy
• Paul deGrandis
• Kevin Lynagh

TODO

• Rules for function definitions (make this more of a lint tool)
• Rules for collection lookup; "2 is a bad smell" see this blog post
• Extract the "when to use" rules from Joy of Clojure
• Leiningen project.clj setting for rule exclusion
• Leiningen project.clj setting for a directory of rules to include
• Analyse ClojureScript files

License

Copyright © 2012 Jonas Enlund

Distributed under the Eclipse Public License, the same as Clojure.