On Mon, Sep 2, 2024 at 4:36 PM vignes waran
<vigneswarank.kar...@gmail.com> wrote:
>
> I have been trying to understand the concept of iterators introduced in the
> new Go 1.23 release, but I’m struggling to comprehend how the iteration call
> happens multiple times and where the boolean value for stopping the loop is
> obtained. Here’s my code snippet for reference:
>
> package main
>
> import "fmt"
>
> func Countdown(v int) func(func(int) bool) {
> fmt.Println("v :", v) // This function runs only one time
> return func(f func(int) bool) {
> for i := v; i >= 0; i-- {
> if !f(i) {
> return
> }
> }
> }
> }
>
> func main() {
> // fmt.Println("Countdown :", Countdown(2))
> for x := range Countdown(2) {
> fmt.Println(x)
> }
> }
>
> I appreciate any help in understanding this concept better. Thanks in
> advance!"
The compiler wraps the loop body into a function closure, more or less like:
func $loop(x int) bool {
fmt.Println(x)
return true
}
It then changes the for statement into Countdown(2)($loop).
For many more details, which are approximately but not precisely what
the Go 1.23 compiler does, see https://research.swtch.com/coro.
Ian
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