First non-repeated character in a string in Go

firstNonRepeat.go

package main

import "fmt"

func firstNonRepeatChar(s string) rune {
	useMap := make(map[rune]bool)
	for _, v := range s {
		_, ok := useMap[v]
		useMap[v] = ok
	}
	for _, v := range s {
		if !useMap[v] {
			return v
		}
	}
	return rune(0)
}

func main() {
	fmt.Printf("%c",firstNonRepeatChar("abca"))
}