Based on https://github.com/DiSiqueira/GoTree

tree.go

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
)

type TreeNode struct {
	Name     string
	Size     int64
	SubNodes []TreeNode
}

func stringTree(object []TreeNode, printFiles bool) (result string) {
	var spaces []bool
	result += stringObjectItems(object, spaces, printFiles)
	return
}

func stringObjectItems(items []TreeNode, spaces []bool, printFiles bool) (result string) {
	for i, f := range items {
		last := (i >= len(items)-1)
		result += stringLine(f.Name, f.Size, spaces, last, printFiles)
		if len(f.SubNodes) > 0 {
			spacesChild := append(spaces, last)
			result += stringObjectItems(f.SubNodes, spacesChild, printFiles)
		}
	}
	return
}

func stringLine(name string, size int64, spaces []bool, last bool, printFiles bool) (result string) {
	for _, space := range spaces {
		if space {
			result += "	"
		} else {
			result += "│	"
		}
	}

	indicator := "├───"
	if last {
		indicator = "└───"
	}
	if printFiles {
		if size > 0 {
			result += fmt.Sprintf("%s%s (%vb)\n", indicator, name, size)
		} else {
			result += fmt.Sprintf("%s%s (empty)\n", indicator, name)
		}
	} else {
		result += fmt.Sprintf("%s%s\n", indicator, name)
	}

	return
}

func walk(dirname string) ([]TreeNode, error) {
	var items []TreeNode
	files, err := ioutil.ReadDir(dirname)
	if err != nil {
		return nil, err
	}
	for _, file := range files {
		var child TreeNode
		child.Name = file.Name()
		child.Size = file.Size()

		if file.IsDir() {
			newNode := filepath.Join(dirname, file.Name())
			child.SubNodes, err = walk(newNode)
		}

		items = append(items, child)
	}
	return items, nil
}

func dirTree(output io.Writer, directory string, printFiles bool) error {
	items, err := walk(directory)
	if err != nil {
		return err
	}
	fmt.Fprintln(output, stringTree(items, printFiles))
	return nil
}

func main() {
	out := os.Stdout
	if !(len(os.Args) == 2 || len(os.Args) == 3) {
		panic("usage go run main.go . [-f]")
	}
	path := os.Args[1]
	printFiles := len(os.Args) == 3 && os.Args[2] == "-f"
	err := dirTree(out, path, printFiles)
	if err != nil {
		panic(err.Error())
	}
}