---
title: Variables
description: Local state management with type inference and explicit mutability.
icon: Variable
---

Variables in Mist are declared with the `let` keyword. Like Rust, variables are immutable by default, and types are written after the name for scannability.

## Basic Declaration

Variables use `let` for automatic type inference. The type annotation is optional — when omitted, the compiler infers the type from the value.

```mist
let x = 42;
let greeting = "Hello Mist";
```

## Mutability

To allow a variable to be reassigned, use `let mut`:

```mist
let mut score = 0;
score = 100;
```

## Explicit Typing

Type annotations are placed after the name:

```mist
let id u64 = 1000234;
let is_active bool = true;
let name *str = "mist";
```

## Arrays

```mist
let list = [1, 2, 3];       // Standard init
let zeros = [0; 10];         // Repeat notation: ten zeroes
```

## Pattern Destructuring

Tuples are destructured using square brackets:

```mist
let [a, b] = (10, "hello");
let [a, [b, c]] = (1, (2, 3));
```

## Key Characteristics

- **Predictable Order**: The `let` keyword signals a binding, followed by the name, optional type, and optional value.
- **Safety First**: Immutability by default prevents accidental state changes.
- **Zero-Cost Inference**: Type inference is handled entirely at compile time.
- **Shadowing**: Mist supports variable shadowing within the same scope.