// lazy_evaluation.go
package main

import (
	"fmt"
)

var resume chan int

func integers() chan int {
    yield := make (chan int)
    count := 0
    go func () {
        for {
            yield <- count
            count++
        }
    } ()
    return yield
}

func generateInteger() int {
    return <-resume
}
func main() {
	resume = integers()
	fmt.Println(generateInteger()) //=> 0
	fmt.Println(generateInteger()) //=> 1
	fmt.Println(generateInteger()) //=> 2
}