https://docs.google.com/presentation/d/1TqCv_ECXBVGw1XOQ-v6rVRyiYGczl4yhDCJIhNLpzaQ/edit#slide=id.gc7f218b544_1_624

go_practice_generics2.go

package main

import (
	"fmt"
)

func Map[T, U any](values []T, mapper func(T) U) []U {
	var result []U
	for _, v := range values {
		result = append(result, mapper(v))
	}
	return result
}

type Tuple[T, U any] struct {
	X T
	Y U
}

func New[T, U any](v1 T, v2 U) *Tuple[T, U] {
	return &Tuple[T, U]{v1, v2}
}

type Number interface {
	int | int32 | int64 | float32 | float64
}

func Max[T Number](x, y T) T {
	if x >= y {
		return x
	}
	return y
}

func main() {
	// 【TRY】マップ関数
	// https://docs.google.com/presentation/d/1TqCv_ECXBVGw1XOQ-v6rVRyiYGczl4yhDCJIhNLpzaQ/edit#slide=id.gc7f218b544_1_560
	var ss []string = Map([]int{10, 20}, func(n int) string {
		return fmt.Sprintf("0x%x", n)
	})
	fmt.Println(ss)

	// 【TRY】Tuple型
	// https://docs.google.com/presentation/d/1TqCv_ECXBVGw1XOQ-v6rVRyiYGczl4yhDCJIhNLpzaQ/edit#slide=id.gc7f218b544_1_578
	var t *Tuple[int, string] = New(10, "hoge")
	fmt.Println(t.X, t.Y)

	// 【TRY】制約の無い型パラメタ
	// https://docs.google.com/presentation/d/1TqCv_ECXBVGw1XOQ-v6rVRyiYGczl4yhDCJIhNLpzaQ/edit#slide=id.gc7f218b544_1_624
	fmt.Println(Max(10, 20))   // 20
	fmt.Println(Max(3.5, 2.5)) // 3.5
}