Go patterns

future.go

package main

import (
	"fmt"
	"time"
)

// Function blocks the execution until the heavy execution is done
func heavySum(a, b int) chan int {

	future := make(chan int, 1)

	go func() {
		time.Sleep(5 * time.Second)
		future <- (a + b)
	}()

	return future
}

func main() {
	fmt.Println("Block until work is done?")
	fmt.Println("Blocks", <-heavySum(12, 12))
	fmt.Println("After")
}

number-generator.go

package main

import (
	"fmt"
	"time"
)

func numGen(to int) chan int {
	yield := make(chan int)

	go func() {
		index := 0

		for index <= to {
			time.Sleep(3 * time.Second)
			yield <- index
			index++
		}
		close(yield)
	}()

	return yield
}

func main() {

	numbers := numGen(30)
	for cur := range numbers {
		fmt.Println("->", cur)
	}

	fmt.Println("After")
}