Golang Genericsサンプル(単方向リスト)

main.go

package main

import (
	"fmt"

	"golang.org/x/exp/constraints"
)

type List[T any] struct {
	head *T
	tail *List[T]
}

func NIL[T any]() *List[T] {
	return &List[T]{nil, nil}
}

func isNil[T any](xs *List[T]) bool {
	return xs.head == nil
}

func genList[T any](xs ...T) *List[T] {
	if len(xs) == 0 {
		return NIL[T]()
	}
	return &List[T]{&xs[0], genList(xs[1:]...)}
}

func sum[T constraints.Integer](xs *List[T]) T {
	if isNil(xs) {
		return 0
	}
	return *xs.head + sum(xs.tail)
}

func main() {
	list := genList(1, 2, 3)
	sumList := sum(list)
	fmt.Printf("%d", sumList)
}