package main

import (
	"bufio"
	"fmt"
	"io"
	"strings"
)

func fba() func() intGen {
	a, b := 0, 1
	return func() int {
		a, b = b, a+b
		return a
	}
}

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)
	return strings.NewReader(s).Read(p)
}
func printFileContents(reader io.Reader) {
	scanner := bufio.NewScanner(reader)
	for scanner.Scan() {
		fmt.Println(scanner.Text())
	}
}

func main() {

	f := fba()
	printFileContents(f)
}

以下是报错

# command-line-arguments
.\main.go:12:9: cannot use func literal (type func() int) as type func() intGen in return argument
.\main.go:38:19: cannot use f (type func() intGen) as type io.Reader in argument to printFileContents:
        func() intGen does not implement io.Reader (missing Read method)

实在是找不到问题所在，我用的go1.13.3，vscode编辑器。