chore: add lox code examples

Author: aymaneelmaini

examples/README.md

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+# KLox Sample Programs
+
+This directory contains example programs demonstrating various features of the KLox language.
+
+## Valid Examples
+
+### Basic Programs
+- **fibonacci.lox** / **example_fibonacci.lox** - Recursive Fibonacci sequence calculator
+- **loops.lox** - For and while loop examples
+- **control_flow.lox** - If/else and control flow examples
+- **operators.lox** - Arithmetic, comparison, and logical operators
+- **functions.lox** - Function declaration and usage
+
+### Advanced Features
+- **closures.lox** - Demonstrates lexical scoping and closures
+- **anonymous_functions.lox** - Lambda/anonymous function examples
+
+### Object-Oriented Programming
+- **classes.lox** - Classes and methods
+- **inheritance.lox** - Class inheritance
+- **super.lox** - Superclass method calls
+- **static_methods.lox** - Static methods on classes
+
+### Native Functions
+- **native_lox.lox** - Using built-in clock() function
+- **native_input.lox** - Using input() for user input
+- **native_scan.lox** - Using scan() for reading input
+
+### Complete Examples
+- **example_quiz.lox** - Interactive quiz program
+- **example_user_db.lox** - User database example
+
+## Error Examples
+
+The `errors/` directory contains programs that demonstrate the beautiful error reporting system:
+
+### Parse Errors
+- **parse_error.lox** - Missing expression after operator
+
+### Runtime Errors
+- **runtime_error_division_by_zero.lox** - Division by zero
+- **runtime_error_undefined_variable.lox** - Accessing undefined variables
+- **type_error.lox** - Type mismatch in operations
+
+## Running Examples
+
+To run a valid example:
+```bash
+java -jar build/libs/klox.jar samples/fibonacci.lox
+```
+
+To see the beautiful error reporting in action:
+```bash
+java -jar build/libs/klox.jar samples/errors/parse_error.lox
+```
+
+To start the interactive REPL:
+```bash
+java -jar build/libs/klox.jar
+```
+
+## Features Demonstrated
+
+- ✓ Variables and scoping
+- ✓ Functions (named and anonymous)
+- ✓ Classes and inheritance
+- ✓ Closures
+- ✓ Loops (for, while)
+- ✓ Conditionals (if/else)
+- ✓ Operators (arithmetic, comparison, logical)
+- ✓ Native functions (clock, println, scan, input)
+- ✓ Static methods
+- ✓ Super keyword for parent class access
+- ✓ Beautiful Rust-style error reporting with source context

examples/anonymous_functions.lox

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+var numbers = 5;
+var double = fn(n) { n * 2 };
+
+println(double(numbers));
+
+var apply = fn(func, value) {
+  func(value)
+};
+
+println(apply(double, 10));

examples/classes.lox

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+class Person {
+  init(name, age) {
+    this.name = name;
+    this.age = age;
+  }
+  
+  introduce() {
+    println("Hi, I'm " + this.name + " and I'm " + this.age + " years old");
+  }
+  
+  birthday() {
+    this.age = this.age + 1;
+    println(this.name + " is now " + this.age);
+  }
+}
+
+var alice = Person("Alice", 30);
+alice.introduce();
+alice.birthday();

examples/closures.lox

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+// Closure example
+// Demonstrates lexical scoping and closures
+
+fun makeCounter() {
+    var count = 0;
+
+    fun increment() {
+        count = count + 1;
+        return count;
+    }
+
+    return increment;
+}
+
+var counter = makeCounter();
+print counter();
+print counter();
+print counter();

examples/control_flow.lox

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+var x = 10;
+var y = 20;
+
+if (x < y) {
+  println("x is less than y");
+}
+
+var counter = 0;
+while (counter < 5) {
+  println("Counter: " + counter);
+  counter = counter + 1;
+}

examples/errors/parse_error.lox

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+// This file demonstrates parse error reporting
+// Missing expression after the + operator
+
+var x = 10
+var y = 20 +
+print x

examples/errors/runtime_error_division_by_zero.lox

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+// This file demonstrates runtime error reporting
+// Division by zero error
+
+var x = 10
+var y = "hello" + x
+var z = 5 / 0
+print z

examples/errors/runtime_error_undefined_variable.lox

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+// This file demonstrates runtime error reporting
+// Undefined variable access
+
+var x = 10
+print x + undefinedVariable

examples/errors/type_error.lox

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+// This file demonstrates runtime type error
+// Cannot add incompatible types in certain operations
+
+var x = "hello"
+var y = 10
+var z = x - y
+print z

examples/example_fibonacci.lox

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+fun fibonacci(n) {
+  if (n <= 1) {
+    n
+  } else {
+    fibonacci(n - 1) + fibonacci(n - 2)
+  }
+}
+
+var start = clock();
+var result = fibonacci(30);
+var elapsed = clock() - start;
+
+println("fibonacci(30) = " + result);
+println("Computed in " + elapsed + " seconds");