異種のデータ型を持つ Go 配列をアンマーシャリングするにはどうすればよいですか?

package main

import (
    "encoding/json"
    "fmt"
)

func decodeJSON(f interface{}) {
    switch vf := f.(type) {
    case map[string]interface{}:
        fmt.Println("is a map:")
        for k, v := range vf {
            checkTypeAndDecode(k, v)
        }
    case []interface{}:
        fmt.Println("is an array:")
        for k, v := range vf {
            checkTypeAndDecode(k, v)
        }
    }
}

func checkTypeAndDecode(k string, v interface{}) {
    switch vv := v.(type) {
    case string:
        fmt.Printf("%v: is string - %q\n", k, vv)
    case int:
        fmt.Printf("%v: is int - %q\n", k, vv)
    default:
        fmt.Printf("%v: ", k)
        decodeJSON(v)
    }
}

func main() {
    my_json := `{
    "an_array":[
    "with_a string",
    {
        "and":"some_more",
        "different":["nested", "types"]
    }
    ]
}`

    var f interface{}
    err := json.Unmarshal([]byte(my_json), &f)
    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println("JSON:")
        decodeJSON(f)
    }
}

JSON:
is a map:
an_array: is an array:
0: is string - "with_a string"
1: is a map:
and: is string - "some_more"
different: is an array:
0: is string - "nested"
1: is string - "types"