Can you give an example of methods for working with channels without using goroutines?

Channels in Go are typically used for communication between goroutines, but they can also be used without launching additional goroutines, for example, for synchronous data transfer.

Example:

package main

import "fmt"

func main() {
    ch := make(chan int)

    // Sending and receiving in the same thread (without goroutines)
    go func() {
        ch <- 42
    }()

    val := <-ch
    fmt.Println(val)
}

However, in this example, a goroutine is used for sending to avoid blocking. If goroutines are not used at all, sending and receiving must happen sequentially, for example:

package main

import "fmt"

func main() {
    ch := make(chan int, 1) // Buffered channel

    ch <- 10  // Send to buffered channel
    val := <-ch // Receive from channel

    fmt.Println(val)
}

Here, the buffered channel allows sending a value without blocking, as there is space in the buffer. Thus, working with channels without goroutines is possible when using buffered channels and sequential send/receive.