quick hack attempting sumtypes in Go

sum.go

package main

import "log"

// enum ShapeKind { Square, Rectangle, Circle };
// struct Shape {
//     int centerx;
//     int centery;
//     enum ShapeKind kind;
//     union {
//         struct { int side; };           /* Square */
//         struct { int length, height; }; /* Rectangle */
//         struct { int radius; };         /* Circle */
//     };
// };

// int getSquareSide(struct Shape* s) {
//     assert(s->kind == Square);
//     return s->side;
// }

// void setSquareSide(struct Shape* s, int side) {
//     s->kind = Square;
//     s->side = side;
// }
type ShapeKind int

const Square ShapeKind = iota
const Rectangle = iota
const Circle = iota

type Shape struct {
	centerx, centery int
}
type ShapeInterface interface {
	GetShape() Shape
}

type ShapeSquare struct {
	Shape
	side int
}

type ShapeRectangle struct {
	Shape
	length, height int
}
type ShapeCircle struct {
	Shape
	radius int
}

func (s ShapeSquare) GetShape() Shape {
	return s.Shape
}
func (s ShapeCircle) GetShape() Shape {
	return s.Shape
}
func (s ShapeRectangle) GetShape() Shape {
	return s.Shape
}
func (s ShapeSquare) GetSide() int {
	return s.side
}
func (s *ShapeSquare) SetSide(side int) {
	s.side = side
}

func main() {
	shapes := make([]ShapeInterface, 0)
	shapes = append(shapes, ShapeSquare{Shape: Shape{0, 0}, side: 1})
	shapes = append(shapes, ShapeCircle{Shape: Shape{0, 0}, radius: 1})
	shapes = append(shapes, ShapeRectangle{Shape: Shape{0, 0}, length: 1, height: 1})
	log.Printf("%+v\n", shapes)
}