<- 到底是个什么符号

package main import ("fmt"; "time") func subtask(done chan<- bool) { ... done <- true } func main() { done := make(chan bool) // return a reference to an underlying data structure go subtask(done) // why not &done? perhaps since (*chan bool) cannot specify direction. <-done } 有直接写 <-done的 package main import ("fmt"; "time") func subtask(done chan<- bool) { ... done <- true } func main() { status := false done := make(chan bool) // return a reference to an underlying data structure go subtask(done) // why not &done? perhaps since (*chan bool) cannot specify direction. status <-done } 也有 status <- done 的，这里教程只是说读和写，那它在还有其他用处吗，为什么可以缩写成<- xxx这种