feat(go): 添加函数类型和计算器实现- 新增 funcTypes.go 文件，定义 calcFunc 类型及其实现

- 新增 funcTypes1.go 文件，使用匿名函数实现计算器逻辑
- 修改 main.go 调用新增的 main1 和 main2 函数- 初始化 structs 模块的 go.mod 文件
- 恢复 structs/main.go 原始内容并保留调试提示注释

09-FuncAndTypes/funcTypes/funcTypes.go

@@ -0,0 +1,34 @@
+package main
+
+import "fmt"
+
+type calcFunc func(float64) float64
+
+func calcWithTax(price float64) float64 {
+	return price + (price * 0.2)
+}
+
+func calcWithoutTax(price float64) float64 {
+	return price
+}
+
+func printPrice(product string, price float64, calculator calcFunc) {
+	fmt.Println("Product:", product, "Price:", calculator(price))
+}
+
+func selectCalculator(price float64) calcFunc {
+	if price > 100 {
+		return calcWithTax
+	}
+	return calcWithoutTax
+}
+
+func main1() {
+	products := map[string]float64{
+		"Kayak":      275,
+		"LifeJacket": 48.95,
+	}
+	for product, price := range products {
+		printPrice(product, price, selectCalculator(price))
+	}
+}

09-FuncAndTypes/funcTypes/funcTypes1.go

@@ -0,0 +1,30 @@
+package main
+
+import "fmt"
+
+func printPrice2(product string, price float64, calculator calcFunc) {
+	fmt.Println("Product:", product, "Price:", calculator(price))
+}
+
+func selectCalculator2(price float64) calcFunc {
+	if price > 100 {
+		var withTax calcFunc = func(price float64) float64 {
+			return price + (price * 0.2)
+		}
+		return withTax
+	}
+	var withoutTax calcFunc = func(price float64) float64 {
+		return price
+	}
+	return withoutTax
+}
+
+func main2() {
+	products := map[string]float64{
+		"Kayak":      275,
+		"LifeJacket": 48.95,
+	}
+	for product, price := range products {
+		printPrice2(product, price, selectCalculator2(price))
+	}
+}

09-FuncAndTypes/funcTypes/main.go

@@ -1,21 +1,6 @@
 package main
 
-import (
-  "fmt"
-)
-
-//TIP <p>To run your code, right-click the code and select <b>Run</b>.</p> <p>Alternatively, click
-// the <icon src="AllIcons.Actions.Execute"/> icon in the gutter and select the <b>Run</b> menu item from here.</p>
-
 func main() {
-  //TIP <p>Press <shortcut actionId="ShowIntentionActions"/> when your caret is at the underlined text
-  // to see how GoLand suggests fixing the warning.</p><p>Alternatively, if available, click the lightbulb to view possible fixes.</p>
-  s := "gopher"
-  fmt.Printf("Hello and welcome, %s!\n", s)
-
-  for i := 1; i <= 5; i++ {
-	//TIP <p>To start your debugging session, right-click your code in the editor and select the Debug option.</p> <p>We have set one <icon src="AllIcons.Debugger.Db_set_breakpoint"/> breakpoint
-	// for you, but you can always add more by pressing <shortcut actionId="ToggleLineBreakpoint"/>.</p>
-	fmt.Println("i =", 100/i)
-  }
-}
+	main1()
+	main2()
+}

10-Structs/structs/go.mod

@@ -0,0 +1,3 @@
+module structs
+
+go 1.22

10-Structs/structs/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+  "fmt"
+)
+
+//TIP <p>To run your code, right-click the code and select <b>Run</b>.</p> <p>Alternatively, click
+// the <icon src="AllIcons.Actions.Execute"/> icon in the gutter and select the <b>Run</b> menu item from here.</p>
+
+func main() {
+  //TIP <p>Press <shortcut actionId="ShowIntentionActions"/> when your caret is at the underlined text
+  // to see how GoLand suggests fixing the warning.</p><p>Alternatively, if available, click the lightbulb to view possible fixes.</p>
+  s := "gopher"
+  fmt.Printf("Hello and welcome, %s!\n", s)
+
+  for i := 1; i <= 5; i++ {
+	//TIP <p>To start your debugging session, right-click your code in the editor and select the Debug option.</p> <p>We have set one <icon src="AllIcons.Debugger.Db_set_breakpoint"/> breakpoint
+	// for you, but you can always add more by pressing <shortcut actionId="ToggleLineBreakpoint"/>.</p>
+	fmt.Println("i =", 100/i)
+  }
+}