Show me the docs

Any Clojure aware editor will show the syntax of a function as you add it to your code. It should also show you the documenation and source code for a function too, so you can understand what it does and how it works.

Clojure functions are documented by adding a string to the function definition. This is refered to as the doc string.

(defn example-function
  "This is the documentation for this function, refered to as a doc string"
  (str "some behaviour"))

Reading the source code for some of the commonly used functions in clojure.core is a great way to discover how to write Clojure

Writing your own documentation

Writing good documentation for your own functions take practice which pays off in the long run.

Write your own function and practice writing a meaningful documentation in the doc string

Reveal answer...

(defn my-function 
  "I must practice writing clear and meaningful documentation for my functions"
  (str "I should wrie better functions too"))

Documentation for the my-function function

The doc & source functions

If you are not using a Clojure aware editor or spend a lot of time in the REPL you can also view the documenation of a function by calling the doc function and see the source by calling the source function.

To use the doc & source functions in the REPL you should be in the user namespace.

On the command line, start a REPL with the command lein repl and then view the documentation for three common functions used in clojure

Make sure you are in the user namespace before calling the doc function. If you are in another namespace, either change back using (ns 'user) or see the next section on using these functions in another namespace.

(doc doc)
(doc map)
(doc filter)
(doc cons)

(source doc)
(source map)

Here is the doc string for doc

Documentation for the function doc

Here is the source code for the source function

Source code for the function source

As the documentaiton for a function is part of its definition, by looking at the source of a function you also get the documentation.

Using doc & source function from another namespace

The doc and source functions are only included in the user namespace. If you switch to another namespace or your editor places you in the current namespace of your project, these funcitons will not be available unless you including core.repl in the current namespace.

From the REPL, evaluate the expression:

(use 'clojure.repl)

You could also require the clojure.repl library in your own code, however if you have a good editor it should provide these features without including this library. Therefore the following code is shown only as an example and not a recommended approch.

(ns foobar
(:require [clojure.repl :refer :all]))

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