Insertion sort in Golang

insertion-sort.go

package main

import (
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

//Usage: insertion-sort 4,3,5,99,16
func main() {
	numbers := os.Args[1]

	var arr []int
	var num int
	var err error
	for _, val := range strings.Split(numbers, ",") {
		num, err = strconv.Atoi(val)

		if err != nil {
			log.Fatal("Failed")
		}

		arr = append(arr, num)
	}

	for j := 1; j < len(arr); j++ {
		key := arr[j]
		i := j - 1

		for i >= 0 && arr[i] > key {
			arr[i+1] = arr[i]
			i = i - 1
		}

		arr[i+1] = key
	}

	fmt.Println(arr)
}