CIDER is the Clojure(Script) Interactive Development Environment that Rocks!

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CIDER extends Emacs with support for interactive programming in Clojure. The features are centered around cider-mode, an Emacs minor-mode that complements clojure-mode. While clojure-mode supports editing Clojure source files, cider-mode adds support for interacting with a running Clojure process for compilation, debugging, definition and documentation lookup, running tests and so on.

CIDER aims to provide an interactive development experience similar to the one you’d get when programming in Emacs Lisp, Common Lisp (with SLIME or Sly), Scheme (with Geiser) and Smalltalk.

Programmers are expected to program in a very dynamic and incremental manner, constantly re-evaluating existing Clojure definitions and adding new ones to their running applications. You never stop/start a Clojure application while using CIDER - you’re constantly interacting with it and changing it.


The canonical way to install CIDER via Emacs's build-in package manager (a.k.a. package.el). Assuming you've setup the required repository (e.g. MELPA), all you need to do is M-x package-install RET cider RET

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Quick Start

The simplest way to start CIDER is via C-c C-x j j. This command will spin an nREPL server and connect CIDER to it.

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CIDER packs a lot of features. Here we'll highlight a few of them.

Code Completion

CIDER provides smart code completion for Clojure and ClojureScript.

Definition and Documentation Lookup

CIDER provides powerful code and documentation lookup facilities.

Interactive Debugger

CIDER ships with a powerful source code debugger inspired by Edebug.

Enhanced REPL

CIDER provides a super-charged REPL experience with all the bells and whistles you can imagine.

Human-friendly Error Messages

CIDER tries to present Clojure's notorious stacktraces in a manner that's less intimidating and more informative.

Test Integration

CIDER gives you the ability to run your tests without ever leaving your editor.

Hacker fame is just cider-jack-in away!

© 2020 Bozhidar Batsov and CIDER contributors. All rights reserved.

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