Channel directions

Context

When using channels as function parameters, you can specify direction: chan<- T (send‑only) or <-chan T (receive‑only). This improves type safety.

Example

Pass a send‑only channel to a producer and a receive‑only channel to a consumer.

Code example

package main

import "fmt"

func producer(out chan<- int) {
    for i := 0; i < 3; i++ {
        out <- i
    }
    close(out)
}

func consumer(in <-chan int) {
    for v := range in {
        fmt.Println(v)
    }
}

func main() {
    ch := make(chan int)
    go producer(ch)
    consumer(ch)
}

Output

0
1
2

Useful links

• Go spec: Channel types
• Go by Example: Channel Directions