Panther Programming Language

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func divide = (lhs: Int, rhs: Int) -> Int <Void> {
	if(rhs == 0){ error; }

	return lhs / rhs;
}


func entry = () #entry -> UI8 {
	const division_result: Int = try divide(12, 0) else 0;

	return division_result as UI8;
}

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interface Shape = #polymorphic {
	func area = (this) -> F32;
	func num_sides = () -> UInt { return 0;	} // method with default
}


type Quad = struct {
	var width: F32;
	var height: F32;


	func area = (this) -> F32 {
		return this.width * this.height;
	}

	func num_sides = () -> UInt { return 4; }


	// implementation of Shape for Quad
	impl Shape{
		area      = area, // defining with an existing method
		num_sides = () -> UInt { return 4; }, // defining with an inline method
	}
}


type Circle = struct {
	var radius: F32;


	func get_area = (this) -> F32 {
		return 3.14 * this.radius * this.radius;
	}

	func get_num_sides = () -> UInt { return 0; }


	// Implementation of Shape for Circle
	impl Shape{
		area = get_area, // method names don't have to be the same
		// using default for Shape.num_sides
	}
}



// this function becomes a template on the shape passed to it
func get_shape_num_sides = (shape: Shape) -> UInt {
	return shape.num_sides();
}


// runtime polymorphism (allowed becuase the interface has attribute `#polymorphic`)
// `shape` is a struct of a pointer to the shape object and a pointer to a vtable
func get_shape_area = (shape: Shape^) -> F32 {
	return shape.area();
}



func entry = () #entry -> UI8 {
	const quad = new Quad{
		width  = 1.0,
		height = 2.0,
	};

	const circle = new Circle{
		radius = 2.0,
	};

	const num_sides_of_quad: UInt = get_shape_num_sides(quad);

	const area_of_circle: F32 = get_shape_area(circle as Shape^);
	
	return 0;
}