1 files changed, 38 insertions, 0 deletions
diff --git a/doc/progs/sieve.go b/doc/progs/sieve.go
new file mode 100644
index 000000000..b31530981
--- /dev/null
+++ b/doc/progs/sieve.go
@@ -0,0 +1,38 @@
+// 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 channel 'ch'.
+func generate(ch chan int) {
+	for i := 2; ; i++ {
+		ch <- i // Send 'i' to channel 'ch'.
+	}
+}
+
+// Copy the values from channel 'in' to channel 'out',
+// removing those divisible by 'prime'.
+func filter(in, out chan int, prime int) {
+	for {
+		i := <-in // Receive value of new variable 'i' from 'in'.
+		if i%prime != 0 {
+			out <- i // Send 'i' to channel 'out'.
+		}
+	}
+}
+
+// The prime sieve: Daisy-chain filter processes together.
+func main() {
+	ch := make(chan int)       // Create a new channel.
+	go generate(ch)            // Start generate() as a goroutine.
+	for i := 0; i < 100; i++ { // Print the first hundred primes.
+		prime := <-ch
+		fmt.Println(prime)
+		ch1 := make(chan int)
+		go filter(ch, ch1, prime)
+		ch = ch1
+	}
+}