IEx or Interactive EliXir gives you the helper h macro which prints the documentation of a given module or function. Documentation is retrieved from @moduledoc or @doc attributes defined in the source code of the module or function.

h can also accept itself as an argument:

iex> h h
                                    def h()

Prints the documentation for IEx.Helpers.

                                defmacro h(term)

Prints the documentation for the given module or for the given function/arity


 #=> Prints documentation for Enum

It also accepts functions in the format fun/arity and, for

 h receive/1
 h Enum.all?/2
 h Enum.all?