package main

import (
	"fmt"
)

type List[T any] struct {
	next *List[T]
	val	T
}

func (l *List[T]) Prepend(v T) *List[T] {
	return &List[T]{next: l, val: v}
}

func (l *List[t]) Len() int {
	count := 0
	for cur := l; cur != nil; cur = cur.next {
		count++
	}
	return count
}

func main() {
	var test_list *List[int]
	fmt.Println(test_list)
	test_list = test_list.Prepend(10)
	fmt.Println(test_list)
	test_list = test_list.Prepend(20)
	fmt.Println(test_list)
	fmt.Printf("The list has %d items\n", test_list.Len())
	test_list = test_list.Prepend(30)
	fmt.Println(test_list)
	
	fmt.Printf("The list has %d items", test_list.Len())
}