| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package main |
| |
| import "fmt" |
| |
| // Send the sequence 2, 3, 4, ... to returned channel |
| func generate() chan int { |
| ch := make(chan int) |
| go func(){ |
| for i := 2; ; i++ { |
| ch <- i |
| } |
| }() |
| return ch |
| } |
| |
| // Filter out input values divisible by 'prime', send rest to returned channel |
| func filter(in chan int, prime int) chan int { |
| out := make(chan int) |
| go func() { |
| for { |
| if i := <-in; i % prime != 0 { |
| out <- i |
| } |
| } |
| }() |
| return out |
| } |
| |
| func sieve() chan int { |
| out := make(chan int) |
| go func() { |
| ch := generate() |
| for { |
| prime := <-ch |
| out <- prime |
| ch = filter(ch, prime) |
| } |
| }() |
| return out |
| } |
| |
| func main() { |
| primes := sieve() |
| for { |
| fmt.Println(<-primes) |
| } |
| } |