package main

//"fmt"

func main() {
	//创建一个channel, 双向的
	ch := make(chan int)

	//双向channel能隐式转换为单向channel
	var writeCh chan<- int = ch //只能写，不能读
	var readCh <-chan int = ch  //只能读，不能写

	writeCh <- 666 //写
	//<-writeCh //err,  invalid operation: <-writeCh (receive from send-only type chan<- int)

	<-readCh //读
	//readCh <- 666 //写， err,  invalid operation: readCh <- 666 (send to receive-only type <-chan int)

	//单向无法转换为双向
	//var ch2 chan int = writeCh //cannot use writeCh (type chan<- int) as type chan int in assignment

}