A module is a named unit of Elixir code that groups functions and other definitions. Every function belongs to a module, which acts somewhat like a namespace. section 2.3.1 section 2.3.2
Defining and calling a module
Define modules with defmodule and functions with def. Compile the source, load the resulting module into iex, and call public functions with ModuleName.function_name(arguments). section 2.3.1
Use module names and boundaries to organize code and control calling syntax:
- Write module names with an uppercase initial; dots can suggest hierarchy and reduce naming clashes, but compiled modules have no recorded hierarchical relationship. section 2.3.1
- Place a module definition in one source file, while allowing multiple module definitions in a single file; compilation produces a separate .beam file for each module. section 2.3.1 section 2.7.1
- Import frequently used modules to call public functions without qualification, or alias long names to reduce repeated module-name noise. section 2.3.5
- Treat module names as aliases for atoms at runtime; BEAM checks loaded modules first, then searches code paths for compiled bytecode. section 2.7.1
Modules provide the unit from which larger OTP applications are assembled. An OTP application contains multiple modules, may depend on other applications, and can start as one system. section 11.1 section 11.1.2
Listing 2.1 Defining a module (geometry.ex)
defmodule Geometry do #1
def rectangle_area(a, b) do #2
a * b #2
end #2
end #3
Shows the minimal defmodule and def structure for a callable Geometry module. section 2.3.1
