A module in Mojo is analogous to a module in languages like Python; it's a single file containing code (functions, structs, etc.) that can be imported and reused in other Mojo files. Key points include:

• Modules are designed to be reusable pieces of code. For example, a module might define a data structure, like MyPair, with associated methods.
• Modules do not typically contain a main() function, as their primary purpose is to be imported into other files that drive the application logic.

Example Breakdown: mymodule.mojo

mojoCopy code
struct MyPair:
    var first: Int
    var second: Int

    fn __init__(inout self, first: Int, second: Int):
        self.first = first
        self.second = second

    fn dump(self):
        print(self.first, self.second)

• struct MyPair defines a simple structure with two integers.
• __init__ is a constructor that initializes a MyPair instance.
• dump is a method that prints the values of the instance.

Importing Modules

You can import modules using the import statement or from ... import ... syntax, similar to Python. The examples show three ways to import and use the MyPair struct from mymodule.mojo:

1. Direct import of a specific symbol: from mymodule import MyPair
2. Importing the entire module: import mymodule
3. Importing with an alias: import mymodule as my

Packages in Mojo

A package in Mojo is a collection of modules in a directory, which must include an __init__.mojo file to be recognized as a package. This structure allows for more organized code and can be compiled into a package file for easier distribution.

Key Points on Packages

• The __init__.mojo file is essential for Mojo to treat a directory as a package.
• Packages can be imported just like modules, and they can be compiled into .mojopkg or .📦 files for portability.
• When compiled into a package file, the package name becomes the filename, which is used for importing.

Practical Applications