## Lox

```c
 // Your first Lox program!
 print "Hello, world!";
```

- Dynamic typing
- Automatic memory management
- Data Types
    - Booleans
    - Numbers
    - Strings
    - Nil
- Expressions
    - Arithmetic
    - Comparison and equality
    - Logical operators
    - Precedence and grouping
- Statements
- Variables
- Control Flow
- Functions
- Closures
- Classes

## A Grammar for Lox expressions

- **Literals**. Numbers,strings,Booleans, and nil
- **Unary expressions.** A prefix ! to perform a logical not, and - to negate a number.
- **Binary expressions.** The infix arithmetic(+,-,*,/) and logic operators (==, !=, <, <=,>,>=)
- **Parentheses.** A pair of ( and ) wrapped around and expression.

    - Syntax tree

      ```
      expression     → literal
      | unary
      | binary
      | grouping ;
    
      literal        → NUMBER | STRING | "true" | "false" | "nil" ;
      grouping       → "(" expression ")" ;
      unary          → ( "-" | "!" ) expression ;
      binary         → expression operator expression ;
      operator       → "==" | "!=" | "<" | "<=" | ">" | ">="
      | "+"  | "-"  | "*" | "/" ;
    
      ```

| Name       | Operators | Associates |
|------------|-----------|------------|
| Equality	  | == !=     | Left       |
| Comparison | > >= < <= | Left       |
| Term       | - +	      | Left       |
| Factor     | / *       | Left       |
| Unary      | ! -       | Right      |

```
expression     → equality ;
equality       → comparison ( ( "!=" | "==" ) comparison )* ;
comparison     → term ( ( ">" | ">=" | "<" | "<=" ) term )* ;
term           → factor ( ( "-" | "+" ) factor )* ;
factor         → unary ( ( "/" | "*" ) unary )* ;
unary          → ( "!" | "-" ) unary
               | primary ;
primary        → NUMBER | STRING | "true" | "false" | "nil"
               | "(" expression ")" ;
```