API Documentation

CIDER provides convenient access to local API documentation for application and Clojure functions as well as online documentation for core Clojure functions, third-party Clojure libraries and Java API's.

We will briefly explore the CIDER commands for viewing documentation.

Let's begin by opening the file doc.clj located in the code/clj/cider-tour/src/cider-tour directory of the GitHub project.

Local API Documentation

In doc.clj position point within (or immediately after) print in the expression (print "I'm here just for documentation\n.") expression and type C-c C-d C-d. In the minibuffer, CIDER prompts for the symbol to lookup documentation and defaults to the symbol at point: print. Hit ENTER to accept the default. CIDER displays a popup-buffer with documentation on the core Clojure function print:

C-c C-d C-d executes the cider-doc command which performs a lookup for documentation metadata embedded within Clojure functions and vars (referred to as "docstrings").

CIDER also provides a link to the print function's source code which resides in the file clojure-1.8.0.jar. For core Clojure functions, cider-doc also provides links to any related functions.

Now let's view documentation for an application-level function:

* Move point to the `(defn is-palindrome? ...)` function definition and type `C-M-x` to evaluate.
* Next, move point within the `is-palidrome?` string on the `(is-palindrome? "racecar")` line, and type `C-c C-d C-d [RET]`

CIDER displays the the documentation for is-palindrome?:

FYI

CIDER provides a major mode (cider-docview-mode) for pop-up buffers that display documentation. This is indicated by (Doc) on the modeline. cider-docview-mode extends the standard Emacs help-mode by providing a 'CiderDoc' menu (and shortcut keys) for navigating documentation and searching symbols.

Online API Documentation

Grimoire

CIDER provides integrated access to documentation in Grimoire- a community-maintained Clojure documentation repository. Grimoire is essentially a searchable reference cheat-sheet. Unlike the cider-doc documentation that we used above, Grimoire's documentation typically includes examples and in-line source code (for functions).

CIDER provides two commands for looking up documentation in Grimoire:

• C-c C-d C-r -- View Grimoire documentation in a popup buffer
• C-c C-d C-w -- View Grimoire documentation in browser

In doc.clj position back on the print function call and type C-c C-d C-r. CIDER displays the Grimoire documentation for print in a popup buffer:

Now type C-c C-d C-w. CIDER displays the Grimoire documentation for print in a browser window:

JavaDoc

Clojure provides Java interop capability via access to Java classes, interfaces and objects. CIDER provides access to the Oracle Java API documentation (a.k.a "JavaDoc").

In doc.clj position point on the string "System/getProperty" and type C-c C-d C-j [RET]. This opens a browser window that loads the JavaDoc for the Java System.getProperty() API.

Documentation Search

CIDER also provides commands for searching symbols. These commands as well the documentation lookup commands that we have explored are accessible from the Cider Interactions >> Documentation menu.