A Tour of Go: https://go-tour-jp.appspot.com/moretypes/23

gistfile1.txt

package main

import (
    "golang.org/x/tour/wc"
    "strings"
)

func WordCount(s string) map[string]int {
    words := make(map[string]int)
    for _, word := range strings.Fields(s) {
        words[word] += 1
    }
    return words
}

func main() {
    wc.Test(WordCount)
}