basics: add more examples about how to use goroutine

basics/default-select/main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"log"
+	"time"
+)
+
+func main() {
+	tick := time.Tick(100 * time.Millisecond)
+
+	boom := time.After(5000 * time.Millisecond)
+
+	for {
+		select {
+		case <-tick:
+			log.Println("tick.")
+		case <-boom:
+			log.Println("boom")
+			return
+		default:
+			log.Println("    .")
+			time.Sleep(50 * time.Millisecond)
+		}
+	}
+}

basics/range-close/main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"log"
+)
+
+func fibonacci(n int, ch chan int) {
+	x, y := 0, 1
+	for i := 0; i < n; i++ {
+		ch <- x
+		x, y = y, x+y
+	}
+	close(ch)
+}
+
+func main() {
+	ch := make(chan int, 10)
+
+	go fibonacci(cap(ch), ch)
+	for i := range ch {
+		log.Println(i)
+	}
+
+	log.Println("Done")
+}

basics/select/main.go

@@ -0,0 +1,32 @@
+package main
+
+import "log"
+
+func fibonacci(ch, quit chan int) {
+	x, y := 0, 1
+	for {
+		select {
+		case ch <- x:
+			x, y = y, x+y
+		case <-quit:
+			log.Println("quit")
+			return
+		}
+	}
+}
+
+func main() {
+	ch := make(chan int, 10)
+
+	quit := make(chan int)
+
+	go func() {
+		for i := 0; i < cap(ch); i++ {
+			log.Println(<-ch)
+
+		}
+		quit <- 0
+	}()
+
+	fibonacci(ch, quit)
+}