My answer of "a tour of Go #41( http://go-tour-jp.appspot.com/#41 )"

gotour_41.go

package main

import (
    "strings"
    "code.google.com/p/go-tour/wc"
)

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

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