Go 基础学习 函数式编程

概述

• 函数式编程

  • 闭包

• 资源管理出错处理

  • defer调用 确保在函数结束时调用

  • defer 先入后出

       

代码

package main
 
import "fmt"
 
func adder() func(int) int {
	sum := 0
	return func(v int) int {
		sum += v
		return sum
	}
}
 
type iAdder func(int) (int, iAdder)
 
func adder2(base int) iAdder {
	return func(v int) (int, iAdder) {
		return base + v, adder2(base + v)
	}
}
 
func main() {
	// a := adder() is trivial and also works.
	a := adder2(0)
	for i := 0; i < 10; i++ {
		var s int
		s, a = a(i)
		fmt.Printf("0 + 1 + ... + %d = %d\n",
			i, s)
	}
}

函数实现接口

package main
 
import (
	"bufio"
	"fmt"
	"io"
	"strings"
 
	"golearn/functional/fib"
)
 
type intGen func() int
 
func (g intGen) Read(
	p []byte) (n int, err error) {
	next := g()
	if next > 10000 {
		return 0, io.EOF
	}
	s := fmt.Sprintf("%d\n", next)
 
	// TODO: incorrect if p is too small!
	return strings.NewReader(s).Read(p)
}
 
func printFileContents(reader io.Reader) {
	scanner := bufio.NewScanner(reader)
 
	for scanner.Scan() {
		fmt.Println(scanner.Text())
	}
}
 
func main() {
	var f intGen = fib.Fibonacci()
	printFileContents(f)
}