go by example part 2

5-go-by-example/15-closures.go

@@ -0,0 +1,29 @@
+package main
+
+import "fmt"
+
+// Go supports anonymous functions, which can form closures. Anonymous functions are useful when you want to define a function inline without having to name it.
+
+// intSeq returns another function, which is defined anonymously in the body of intSeq
+// the returned function closes over the variable i to form a closure
+func intSeq() func() int {
+	i := 0
+	return func() int {
+		i++
+		return i
+	}
+}
+
+func main() {
+	// call intSeq, assigning the result (a function) to nextInt
+	nextInt := intSeq()
+
+	// see the effect of the closure
+	fmt.Println(nextInt())
+	fmt.Println(nextInt())
+	fmt.Println(nextInt())
+
+	// confirm that the state is unique to that particular function
+	newInts := intSeq()
+	fmt.Println(newInts())
+}