## 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 documentation 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.

> **Note** 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.

```clojure
(doc doc)
(doc map)
(doc filter)
(doc cons)

(source doc)
(source map)
```

  Here is the doc string for `doc`

![Documentation for the function doc](../images/clojure-playground-doc-doc.png)

  Here is the source code for the `source` function

![Source code for the function source](../images/clojure-playground-source-source.png)

 > **Hint** As the documentation 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 functions 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 approach.

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