ElDoc

Eldoc is a buffer-local minor mode that helps with looking up Lisp documentation. When it is enabled, the echo area displays some useful information whenever there is a Lisp function or variable at point; for a function, it shows the argument list, and for a variable it shows the first line of the variable's documentation string.

CIDER provides a Clojure backend for ElDoc that works out-of-the box, as long as eldoc-mode is enabled.

Enabling ElDoc

global-eldoc-mode is enabled by default in Emacs 25.1, so you don't really have to do anything to enable it.

It will in both source and REPL buffers.

Configuring ElDoc

• CIDER also would show the eldoc for the symbol at point. So in (map inc ...) when the cursor is over inc its eldoc would be displayed. You can turn off this behaviour by:

(setq cider-eldoc-display-for-symbol-at-point nil)

• CIDER respects the value of eldoc-echo-area-use-multiline-p when displaying documentation in the minibuffer. You can customize this variable to change its behaviour.

eldoc-echo-area-use-multiline-p	Behaviour
t	Never attempt to truncate messages. Complete symbol name and function arglist or variable documentation will be displayed even if echo area must be resized to fit.
nil	Messages are always truncated to fit in a single line of display in the echo area.
truncate-sym-name-if-fit or anything non-nil	Symbol name may be truncated if it will enable the function arglist or documentation string to fit on a single line. Otherwise, behavior is just like t case.

• CIDER will try to add expected function arguments based on the current context (for example for the datomic.api/q function where it will show the expected inputs of the query at point), if the variable cider-eldoc-display-context-dependent-info is non-nil:

(setq cider-eldoc-display-context-dependent-info t)