Исходники и презентации

lessons/functions/pure_function/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+)
+
+var cache = map[int]struct{}{}
+
+func dirtySum(x, y *int) int {
+	result := *x + *y
+
+	// mutations of data (1)
+	*x = 0
+	*y = 0
+
+	// logging or files/network (2)
+	fmt.Println(result)
+
+	// global variables (3)
+	cache[result] = struct{}{}
+
+	// dependencies on parameters (4)
+	os.Getenv("parameter")
+
+	// unpredictable result (5)
+	result += rand.Intn(100)
+
+	return result
+}
+
+func pureSum(x, y int) int {
+	return x + y
+}
+
+func main() {
+	x := 13
+	y := 12
+	fmt.Println(dirtySum(&x, &y))
+
+	fmt.Println(pureSum(13, 12))
+}