Programming Challenge: Launch 4 threads, goroutines, coroutines, or whatever your language uses for concurrency, in addition to the main thread. In the first 3, add numbers together (see sample code below) and pass the results to the 4th thread. That 4th thread should receive the 3 results, add the numbers together, format the results as a strin…

goroutines2.go

// Steve Phillips / elimisteve
// 2013.01.03

// Programming Challenge: Launch 4 threads, goroutines, coroutines, or whatever your language uses for concurrency,
// in addition to the main thread. In the first 3, add numbers together (see sample code below) and pass the results
// to the 4th thread. That 4th thread should receive the 3 results, add the numbers together, format the results as
// a string (see sample code), and pass the result back to `main` to be printed.
//
// Do this as succinctly and readably as possible. _Go!_ #golang #programming #concurrency #challenge
package main

import "fmt"

// intDoubler doubles the given int, then sends it through the given channel
func intDoubler(ch chan int, n int) {
    ch <- n*2
}

func main() {
    // Make channel of ints
    ch := make(chan int)
    answer := make(chan string)

    // Spawn 3 goroutines (basically threads) to process data in background
    go intDoubler(ch, 10)
    go intDoubler(ch, 20)
    go func(a, b int) { ch <- a+b }(30, 40) // Take 2 ints, write sum to `ch`

    // Create anonymous function on the fly, launch as goroutine!
    go func() {
        // Save the 3 values passed through the channel as x, y, and z
        x, y, z := <-ch, <-ch, <-ch
        // Calculate answer, write to `answer` channel
        answer <- fmt.Sprintf("%d + %d + %d = %d", x, y, z, x+y+z)
    }()

    // Print answer resulting from channel read
    fmt.Printf("%s\n", <-answer)
}

Would be interesting to see this done with http://libmill.org/ !