在golang中获取未定义的rand.Shuffle

Question

So I have a slice of letters and want to shuffle them. I've implemented this code snippet:

rand.Shuffle(len(letters), func(i, j int) {
    letters[i], letters[j] = letters[j], letters[i]
)}

When running the program it gets stuck at the first line saying: "undefined: rand.Shuffle". in my import declaration i have imported "math/rand" I also run this code snippet before the snippet with a problem:

rand.Seed(seed)

Where "seed" is given earlier in the code.

Also what i want is to shuffle a word but don't touch the first and last letter. Is there an easy solution to this. I have written the code like this:

rand.Shuffle(len(letters), func(i, j int) {
    if i > 0 && i < (len(letters) - 1) && j > 0 && j < (len(letters) - 1){
        letters[i], letters[j] = letters[j], letters[i] 
    }
})

Full code:

import (
    "math/rand"
    "strings"
    "regexp"
)

func splitText(text string) []string {
    re := regexp.MustCompile("[A-Za-z0-9']+|[':;?().,!\\ ]")
    return re.FindAllString(text, -1)
}

func scramble(text string, seed int64) string {
token := splitText(text)
rand.Seed(seed)
if len(token) != 0{
    for i := 0; i < len(token); i++{
        word := token[i]
        if len(word) > 3{
            letters := strings.Split(word, "")
            rand.Shuffle(len(letters), func(i, j int) { 
                if i > 0 && i < (len(letters) - 1) && j > 0 && j < (len(letters) - 1){
                    letters[i], letters[j] = letters[j], letters[i] 
                }
            })
            token[i] = strings.Join(letters, "")
        }
    }
}

returnString := strings.Join(token, "")
return returnString

}

Answer 1

Go 1.10 Release Notes (February 2018)

Minor changes to the library

math/rand

The new Shuffle function and corresponding Rand.Shuffle method shuffle an input sequence.

---

For the rand.Shuffle function, you need at least Go 1.10.

Run go version to check your version.