Erlang modules

Each Erlang Programming source file

utility.erl

is required to be a separate module. Modules are created with the module statement.

-module(utility).         % 1
-export([rotate/1]).      % 2
                          % 3
rotate([H|T]) ->          % 4
    T ++ [H].             % 5

compile with

    c(utility).

run with

    utility:rotate([1,2,3]).

and get

    [2,3,1].

"utility" is the module created by the file utility.erl

utility functions like rotate can be imported elsewhere with:

    -import(utility).

so now we do not need to use the "utility:" prefix. Importing modules is not generally recommended. This is very similar to python and Java imports.