---
title: Modules & Imports
description: Module declarations, imports, re-exports, include directives, and module resolution rules.
icon: FolderTree
---

Mist's module system was created to fix Rust's dreaded parent-declared module system, files declare themselves and their publicity via `pub module my_mod;` as the first statement.


```mist
// Declare a module
pub module foo;

// Import
use std::collections::HashMap;

// Re-exporting import (alias)
pub use my_module::MyType;
```

### Include Directives

Mist supports C-style include directives for 

```mist
// Global include (std::Display)
// Includes all of the items *inside* the path
#include <std/fmt>

// Use include (std::Display)
// Includes *the path* itelf to the root.
#use std::fmt::Display;

// Local include
// Textual include, transpiles to rust include! macro via .rs extension
#include "my_local_module.mist"
```

Include directives allow you to bring in external code without using the module system, which is useful for C interop and local file organization.

### Module Resolution

Mist maps the module tree to Rust's module system:

| Mist Path                    | Rust Output                  |
|------------------------------|------------------------------|
| `src/main.mist`              | `.mist/src/main.rs`          |
| `src/utils/package.mist`     | `.mist/src/utils/mod.rs`     |
| `pub module foo;`            | `.mist/src/foo.rs`           |

A `package.mist` file acts as a directory's module root, analogous to `mod.rs`, but it's not required, as long as the directory contains `.mist` files, it will auto generate `mod.rs`.

#### *💡 Tip*: File names don't matter, `module my_mod` determines the name.