How to Create Modules in Rust with mod

Create a module by declaring mod module_name; in your source file and placing the code in a file named module_name.rs or a directory named module_name containing a mod.rs file. Use pub to make items inside the module accessible from outside.

// src/lib.rs
pub mod kinds {
    pub enum PrimaryColor {
        Red,
        Yellow,
        Blue,
    }
}

pub mod utils {
    use crate::kinds::*;

    pub fn mix(c1: PrimaryColor, c2: PrimaryColor) {
        // Implementation here
    }
}

// src/kinds.rs (if using separate file) pub enum PrimaryColor { Red, Yellow, Blue, }

// src/utils.rs (if using separate file) use crate::kinds::*;

pub fn mix(c1: PrimaryColor, c2: PrimaryColor) { // Implementation here }

Modules let you organize your code into logical groups, like folders in a file system, so your project stays clean and manageable. You use them to hide internal details and only share the specific functions or data that other parts of your program need to see. Think of it like a kitchen where you keep the messy prep work hidden behind the counter and only serve the finished dishes to customers.