composition via embedding instead of inheritance

---

examples/struct-compose/struct_compose.go

package main

import "fmt"

type myPoint struct {
    x int
    y int
}

type myOther struct {
    x float32
    z int
}

type myCircle struct {
    myPoint
    myOther
    r int
}

func main() {
    p1 := myPoint{
        x: 1,
        y: 2,
    }
    c1 := myCircle{}
    c1.myPoint.x = 3
    c1.myOther.x = 6
    c1.y = 4
    c1.r = 5

    fmt.Println(p1)
    fmt.Println(c1)

    // c2 := myCircle{
    //     myPoint: myPoint{x: 6, y: 7},
    //     r:       8,
    // }
    // fmt.Println(c2)

}

{1 2}
{{3 4} 5}
{{6 7} 8}