clooj is a small, simple IDE (integrated development environment) for the clojure programming language, available for free download. clooj is written entirely in clojure and uses a swing-based GUI. It is cross-platform (assuming Java 1.6 or 1.7 has been installed on your operating system), and runs as a standalone application. The application is a single jar file that can be launched by double-clicking its file icon or by running java -jar clooj-XXX-STANDALONE.jar from the command line.

The clooj window contains three columns. The left-most column is a tree showing clojure projects and the source files they contain. The middle column is the source file editor. The right column displays inputs and outputs of clojure REPLs (read-evaluate-print loops).

The source code editor offers a few simple things to make writing clojure code easier:

• A non-traditional bracket-matching feature highlights in gray those brackets that contain the innermost form you are currently editing, and the argument list for the function or macro at the head of the form is displayed.
• Mismatched or unmatched brackets are highlighted in pink.
• cmd+[ indents, and cmd+] unindents.
• cmd+\ cleans up indentation.
• Automatically comment-out (and un-comment-out) multiple lines.
• When newlines are entered, the next line is automatically indented.
• Press ctrl-ENTER to send either the nearest root form or the selected text to the REPL.
• Double-clicking a paren causes its form to be selected.
• Source files are continuously saved in the background to prevent accidental loss of your work in the event of a crash.
• Syntax highlighting (using the RSyntaxTextArea library).

Each clojure project corresponds to a project directory somewhere in the file system, containing a src directory. Inside the src directory is the source code hierarchy, composed of directories and .clj files. Note this directory structure is completely compatible with the lein build tool for clojure. We recommend the use of lein in alongside the clooj editor. Clicking different source files in the projects tree will automatically change the source file currently being edited, as well as switch the REPL to the appropriate namespace.

The upper part of clooj's REPL display column shows the REPL history (inputs and outputs) and the lower part is a text area for inputting forms into REPL. clooj runs a single REPL at a time. By choosing "Restart REPL" you cause the current REPL's process to be shut down and a new REPL to be launched. The new REPL's working directory will be located in the main directory of the currently selected project. If lein is installed, the new REPL's classpath will automatically include the full lein classpath.

clooj can help you search for functions and other names, provide documentation for these names, and auto-complete your code. (This feature is in the early stages of development.) When help is activated, a list of available names similar to the local text is shown at left. At right, documentation and source code is shown for the selected name. Press TAB or shift+TAB to browse through the list, then press ENTER to replace what you have typed with the name you have selected. Press ESC to get out of help mode.

clooj is a work in progress. Please post any suggestions or criticisms to the clooj Google group or to the github issues list.

All feedback is much appreciated. Code contributions in the form of github pull requests are also very welcome!

If you want to start building and working on clooj, then please read the building clooj from source wiki page.

-- Arthur Edelstein