---
title: Modules & Imports
description: Organizing code across files with module declarations and path-based imports.
icon: FolderTree
---

Mist organizes code through a file-system based module system with explicit path imports.

## The Module System

Each `.mist` file in `src/` corresponds to a module. The module tree mirrors the file hierarchy. Directories can be declared as submodules using `mod`.

### File-Based Modules

The file `src/main.mist` is the crate root. Other files are discovered through `mod` declarations or by name.

### Declaring Submodules

```mist
// src/main.mist
mod network;
mod database;
```

## Imports

Use the `use` keyword with a path to bring items from other modules or external crates into scope.

```mist
use std::fs;
use std::process;
use std::path::Path;
use std::collections::HashMap;

// Import specific items
use my_module::Helper;
```

### Visibility

Items can be re-exported with a visibility modifier on the import:

```mist
pub use internal::format;
```

## Sidefiles

Any non-`.mist` file in `src/` (e.g., `.rs`, `.toml`, data files) is treated as a **sidefile** — it is copied directly into the output directory `.mist/src/` during transpilation. This allows you to keep Rust helper files or configuration alongside your Mist source.

```text
src/
├── main.mist
├── helper.rs        # copied to .mist/src/helper.rs
└── config/
    └── data.json    # copied to .mist/src/config/data.json
```

## Project Structure

A typical Mist project looks like this:

```
my-project/
├── Cargo.toml
├── src/
│   ├── main.mist
│   ├── lib/
│   │   ├── parser.mist
│   │   └── helper.rs
│   └── _header.rs
└── .mist/
    └── src/
        ├── main.rs        # transpiled output
        ├── lib/
        │   ├── parser.rs
        │   └── helper.rs
        └── _header.rs
```

The `.mist/src/` directory contains the transpiled Rust output. `_header.rs` is a special file that provides IDE support for Rust Analyzer.