REPL Configuration

Normally, when you first establish a REPL connection, the REPL buffer is auto-displayed in a separate window. You can suppress this behaviour like this:

If you want the REPL buffer to be auto-displayed, but don’t want it to be focused, use this:

By default C-c C-z will display the REPL buffer in a different window. You can make C-c C-z switch to the CIDER REPL buffer in the current window:

You can customize the REPL buffer prompt by setting cider-repl-prompt-function to a function that takes one argument, a namespace name. For convenience, CIDER provides three functions that implement common formats:

By default, CIDER uses cider-repl-prompt-default.

You may, of course, write your own function. For example, in leiningen there are two namespaces with similar names - leiningen.classpath and leiningen.core.classpath. To make them easily recognizable you can either use the default value or you can opt to show only two segments of the namespace and still be able to know which is the REPL’s current namespace. Here is an example function that will do exactly that:

You can control the TAB key behavior in the REPL using the cider-repl-tab-command variable. While the default command cider-repl-indent-and-complete-symbol should be an adequate choice for most users, it’s very easy to switch to another command if you wish to. For instance if you’d like TAB to only indent (maybe because you’re used to completing with M-TAB) use the following:

Prior to version 0.21.0, the REPL buffer would be automatically re-centered whenever any output was printed, so that the prompt was on the bottom line of the window, displaying the maximum possible amount of output above it. This is no longer the default behaviour — you can now replicate it by setting the built-in option scroll-conservatively, for example:

You can change the string used to prefix REPL results:

Which then results in the following REPL output:

By default, REPL results have no prefix.

The REPL buffer name has the format *cider-repl project-name*. You can change the separator from a space character to something else by setting nrepl-buffer-name-separator.

The REPL buffer name can also display the port on which the nREPL server is running. The buffer name will look like *cider-repl project-name:port*.

Normally, code in the REPL is font-locked the same way as in clojure-mode. Before CIDER 0.10, by default, REPL input was font-locked with cider-repl-input-face (after pressing Return) and results were font-locked with cider-repl-result-face. If you want to restore the old behaviour use:

Note that enabling font-locking in the REPL can negatively impact performance.

By default the REPL always prints the results of your evaluations using the printing function specified by cider-print-fn.

!!! Note

You can temporarily disable this behaviour and revert to the default behaviour (equivalent to clojure.core/pr) using M-x cider-repl-toggle-pretty-printing.

If you want to disable using cider-print-fn entirely, use:

Note well that disabling pretty-printing is not advised. Emacs does not handle well very long lines, so using a printing function that wraps lines beyond a certain width (i.e. any of them except for pr) will keep your REPL running smoothly.

See this for more information on configuring printing.

Starting with CIDER 0.17 (Andalucía) expressions that evaluate to images will be rendered as images in the REPL. You can disable this behavior if you don’t like it.

Alternatively, you can toggle this behaviour on and off using M-x cider-repl-toggle-content-types.

Normally, the CIDER REPL will start in the user namespace. You can supply an initial namespace for REPL sessions in the repl-options section of your Leiningen project configuration:

Ordinarily, Return immediate sends a form for evaluation. If you want to insert a newline into the REPL buffer as you’re editing, you can do so using C-j. If you are entering a lot of longer forms that span multiple lines, it may be more convenient to change the keybindings:

This will make Return insert a newline into the REPL buffer and C-Return send the form off for evaluation.

Note that CIDER writes the history to the file when you kill the REPL buffer, which includes invoking cider-quit, or when you quit Emacs.

By default cider-repl-set-ns won’t require the target ns, just set it. That’s done with the assumption that you’ve probably evaluated the ns in question already before switching to it (e.g. by doing C-c C-k in its source file). If you want to change this behaviour (to avoid calling cider-repl-set-ns and then (require 'my-ns) manually), you can set: