---
title: Control Flow
description: Directing execution with expression-based logic, pattern matching, and traditional loop structures.
icon: Split
---

Control flow in Mist provides a bridge between C-style procedural logic and Rust's expression-oriented design. Blocks, if statements, while/for/loop loops, and match expressions all support statement bodies.

## Conditionals

The `if` statement evaluates a boolean expression:

```mist
if (score > 50) {
    println!("Pass");
} else if (score == 50) {
    println!("Borderline");
} else {
    println!("Fail");
}

// Single-statement body (no braces needed)
if (is_active) println!("Running");

// Expression body (implicit return)
let result = if (valid) { "ok" } else { "err" };
```

## Match

The `match` statement provides exhaustive pattern matching with support for multiple patterns per arm via `|`:

```mist
match (task_state) {
    TaskState::Pending => { println!("Queued"); }
    TaskState::Failed { reason, code } => {
        println!("Error {}: {}", code, reason);
    }
    TaskState::NotResponding | TaskState::Progress => {
        draw_loading();
    }
    _ => { println!("Other state"); }
}
```

Patterns support destructuring, or-patterns, and wildcards:

```mist
let x = 2;
let result;

match (x) {
    1 => { result = 10; }
    2 => { result = 20; }
    3 => { result = 30; }
    _ => panic!();
}
```

## Loops

### Loop

An infinite loop construct:

```mist
loop {
    println!("forever");
    if (done) break;
}
```

### For-In Loop

For loops iterate over an expression using the `pattern : expr` syntax:

```mist
for (i : 0..4) {
    sum += i;
}

// With pattern destructuring
for ([k, _] : pairs) {
    keys += k;
}
```

### While Loop

```mist
while (count < 5) {
    count++;
}

while (active) {
    wait_for_event();
}
```

## Jump Statements

- **`return`**: Exits the current function, optionally passing back a value.
- **`break`**: Terminates the innermost looping construct.
- **`continue`**: Skips the remainder of the current loop iteration.

## Key Characteristics

- **Statement Bodies**: If, while, for, and loop branches can omit braces for single statements or expressions.
- **Implicit Returns**: Expression bodies (without `;`) implicitly return their value.
- **Pattern Integration**: Loops and match arms utilize Mist's pattern system for data destructuring.
- **Multiple Patterns**: Match arms support `|` for matching multiple patterns.