As the infomercials always say, "But wait, there's more!" If simultaneous Clojure and ClojureScript REPLs, interactive programming, code completion, stacktrace navigation, test running, and debugging weren't enough for you, CIDER delivers several additional features.
Evaluating Clojure Code in the Minibuffer
You can evaluate Clojure code in the minibuffer at almost any time
cider-read-and-eval (bound in
cider-mode buffers to
C-c M-:). TAB completion will work in the minibuffer,
just as in REPL and source buffers.
Typing C-c C-v . in a Clojure buffer will insert the defun at point into the minibuffer for evaluation. This way you can pass arguments to the function and evaluate it and see the result in the minibuffer.
You can also enable other convenient modes in the minibuffer. For
instance, you might want to have both
available to you:
(add-hook 'eval-expression-minibuffer-setup-hook #'eldoc-mode) (add-hook 'eval-expression-minibuffer-setup-hook #'paredit-mode)
Using a Scratchpad
CIDER provides a simple way to create a Clojure scratchpad via the
cider-scratch command. This is a great way to play
around with some code without having to create source files or pollute
the REPL buffer and is very similar to Emacs's own
Typing C-c C-m after some form in a source buffer or the
REPL will show you the macro expansion of the form in a new
buffer. You'll have access to additional keybindings in the macro
expansion buffer (which is internally using
|g||The prior macro expansion is performed again and the current contents of the macro expansion buffer are replaced with the new expansion.|
|Undo the last in-place expansion performed in the macroexpansion buffer.|
Typing C-c M-i after some form in a source buffer or the
REPL will show you the structure for the result of the form in a new
buffer. You can also use C-u C-c M-i to inspect the result
of the current top-level form and C-u C-u C-c M-i to read
an expression from the minibuffer and inspect its result. You'll have
access to additional keybindings in the inspector buffer (which is
|Tab or Shift-Tab||Navigate inspectable sub-objects|
|l||Pop to the parent object|
|g||Refresh the inspector (e.g. if viewing an atom/ref/agent)|
|SPC||Jump to next page in paginated view|
|M-SPC||Jump to previous page in paginated view|
|s||Set a new page size in paginated view|
Displaying Local Values with Enlighten Mode
Enlighten Mode displays the value of locals in realtime, as your code runs. This feature is somewhat similar to a feature in the Light Table editor.
To turn it on, issue M-x
evaluate your functions one at a time using C-M-x or
C-x C-e. Note that C-c C-k won't work.
That's it! Once your code executes, the regular old buffer on the left will turn into the brilliant show of lights on the right.
|Enlighten Mode Disabled||Enlighten Mode Enabled|
To stop displaying the locals you'll have to disable
and reevaluate the definitions you had instrumented previously.
You can also trigger this on specific functions (without having to turn on the
minor mode) by writing
#light before the
(def and re-evaluating
While Clojure's and CIDER's interactive programming style means you'll restart your application far less often than with other languages and development environments, sometimes you'll want to clean everything up and reload one or more namespaces to ensure that they are up to date and there are no temporary definitions hanging around.
Typing C-c M-n r or C-c M-n M-r will invoke
cider-ns-refresh and reload all modified Clojure files on the
Adding a prefix argument, C-u C-c M-n n, will reload all the namespaces on the classpath unconditionally, regardless of their modification status.
Adding a double prefix argument, C-u C-u M-n n, will first clear the state of the namespace tracker before reloading. This is useful for recovering from some classes of error that normal reloads would otherwise not recover from. A good example is circular dependencies. The trade-off is that stale code from any deleted files may not be completely unloaded.
The above three operations are analogous to
(followed by a normal refresh), respectively.
You can define Clojure functions to be called before reloading, and after a
successful reload, when using
(setq cider-ns-refresh-before-fn "user/stop-system!" cider-ns-refresh-after-fn "user/start-system!")
These must be set to the namespace-qualified names of vars bound to functions of no arguments. The functions must be synchronous (blocking), and are expected to be side-effecting - they will always be executed serially, without retries.
By default, messages regarding the status of the in-progress reload
will be displayed in the echo area after you call
cider-ns-refresh. The same information will also be recorded in the
*cider-ns-refresh-log* buffer, along with anything printed to
You can make the
*cider-ns-refresh-log* buffer display automatically
after you call
cider-ns-refresh by setting the
cider-ns-refresh-show-log-buffer variable to a non-nil value. This
will also prevent any related messages from also being displayed in
the echo area.
(setq cider-ns-refresh-show-log-buffer t)
By default, CIDER will prompt for whether to save all modified Clojure
buffers. You can customize this behavior with
cider-ns-refresh may not work for you. If you're looking
for a bit more forceful reloading the
cider-ns-reload-all commands can be used instead. These commands
(require ... :reload) and
... :reload-all) commands at the REPL.
Tracing Function Execution
You can trace the arguments supplied to and the result values produced by functions using C-c M-t v. CIDER will prompt you for the name of the function you want to trace, defaulting to the previous top-level definition.
Invoking C-c M-t v again for the same function will result in the function being untraced.
You can also use C-c M-t n to toggle tracing on and off for an entire namespace.
Browsing the Classpath
You can easily browse the items on your classpath with the command
Here you can see it in action:
Press RET on a classpath entry to navigate into it.
You can browse the contents of any loaded namespace with the command
cider-browse-ns. CIDER will prompt you for the namespace
You can also browse all available namespaces with M-x
There are a bunch of useful keybindings that are defined in browser buffers.
|d||Display documentation for item at point.|
|RET||Browse ns or display documentation for item at point.|
|s||Go to definition for item at point.|
|^||Browse all namespaces.|
|n||Go to next line.|
|p||Go to previous line.|
Browsing the Clojure Spec Registry
If you are using Clojure 1.9 or newer you can browse the Clojure spec registry.
If you already know which spec you're looking for, you can type
cider-browse-spec and CIDER will prompt you for a
spec name and then drop you into the spec browser.
If you aren't quite sure which spec you want, you can type
cider-browse-spec-all. CIDER will then prompt you for
a regex and will filter out all the spec names that don't match.
Once in the browser you can use your mouse or the keybindings below to navigate deeper.
|RET||Browse the spec at point.|
|^||Go up in the navigation stack.|
|n||Go to next spec.|
|p||Go to previous spec.|
|e||Generate an example for the current browser spec.|
If your project includes the
org.clojure/test.check library, you can
type e when browsing a spec to generate an example that
meets the spec.
Generating Documentation Cross References
Sometimes in your documentation strings, you'd like to be able to
point other programmers at different definitions. If you specify the
name of a definition in backticks (
`), CIDER will convert these
references into live links when it displays the documentation string
in the documentation buffer.
If the name is in another namespace, then you'll have to include the fully qualified name in the docstring.
Example function with a docstring containing references:
(defn test-fn "Test function. Also see: `clojure.core/map`, `clojure.core/reduce`, `defn`. You can reference variables like `thor`, `kubaru.data.zookeeper/yoda`. Also works with references to java interop forms, `java.lang.String/.length`."  (+ 1 1))
You can change the delimiters that CIDER uses to find references if
you don't like using backticks. Simply update the regexp in
cider-doc-xref-regexp to match your preferred format. The first
group of the regexp should always match the cross-reference name. For
example, if you want to want to use
Codox's delimiter style
[[...]]) instead of backticks, the regexp would be:
(setq cider-doc-xref-regexp "\\[\\[\\(.*?\\)\\]\\]")