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Title: 2 Lexical Structure
Prev: Overview
Next: Primitive Types
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## 2. Lexical Structure

### 2.1 Comments
```
// Single-line comment
```

### 2.2 Identifiers

**Regular Identifiers**
- Start with letter or underscore: `[a-zA-Z_][a-zA-Z0-9_]*`
- Case-sensitive
- When encountered, identifiers are executed immediately

**Identifier Literals**
- Prefix with `::` to push the identifier itself onto the stack instead of executing it
- Syntax: `::name` pushes the identifier `name` as a value
- Example: `::Addable` pushes the identifier `Addable` onto the stack
- Example: `::Point` pushes the identifier `Point` onto the stack

> **Advanced Usage**: See [Section 11.2](./advanced_topics.html#112-identifier-literals) for complete identifier literal rules and context-dependent behavior.

### 2.3 Literals

**Integer Literals**

```
42          // i64 (default)
42:i32      // Annotate as i32
0xFF        // hexadecimal
0b1010      // binary
```

**Floating Point Literals**
```
3.14        // f64 (default)
3.14:f32    // Annotate as f32
```

**String Literals**
```
"hello world"
"escape sequences: \n \t \\ \""
```

**Escape Sequences**
- `\n` - Newline (LF)
- `\r` - Carriage return (CR)
- `\t` - Tab
- `\\` - Backslash
- `\"` - Double quote
- `\'` - Single quote
- `\0` - Null character
- `\xNN` - Hexadecimal byte (e.g., `\x41` for 'A')
- `\u{NNNN}` - Unicode code point (e.g., `\u{1F600}` for 😀)

**Boolean Literals**
```
true
false
```

**Array Literals**

```
[1 2 3 4 5]              // array of i32
[1.0 2.0 3.0]            // array of f64
[[1 2] [3 4]]            // 2D array
```

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