package main

import (
	"fmt"
	"golang.org/x/exp/constraints"
)

func main() {

}

// Scale returns a copy of s with each element multiplied by c.
// This implementation has a problem, as we will see.
func Scale[E constraints.Integer](s []E, c E) []E {
	r := make([]E, len(s))
	for i, v := range s {
		r[i] = v * c
	}
	return r
}

type Point []int32

func (p Point) String() string {
	// Details not important.
	return ""
}

// ScaleAndPrint doubles a Point and prints it.
func ScaleAndPrint(p Point) {
	r := Scale(p, 2) //等价于r := Scale[int32](p, 2)
	// 下面这行导致编译报错
	// r.String undefined (type []int32 has no field or method String)
	fmt.Println(r.String()) // DOES NOT COMPILE
}