[] map [string] float64文字不是类型

Question

我正在尝试通过使用在另一篇文章Golang create a slice of maps上看到的方法，来创建map[string]float64的切片。

我试图将其更改为map [string] interface {}，但随后提示

cannot use distmap (type map[string]float64) as type map[string]interface {} in append

我是Go的新手。我以为interface {}可以保留任何值，为什么在这种情况下不能容纳float64？

minDistance := make([]map[string]interface{}, 0, factorial(len(cities)))
for _, city := range cities {
    for k, v := range distances {
        var c []string
        var d []float64
        if strings.HasPrefix(k, city) {
            c = append(c, strings.Split(k, "+")[1])
            d = append(d, v)
        }
        var min float64
        index := 0
        if units == "mi" {
            min = 12450.5
        } else {
            min = 20037.5
        }
        for i, dist := range d {
            if dist < min {
                min = dist
                index = i
            }
        }
        distmap := map[string]float64{city + "+" + c[index]: min}
        minDistance = append(minDistance, distmap)
    }
    // fmt.Printf("Distance between %s: %f %s\n", k, v, units)
}

编译时出错：

.\main.go:151:42: []map[string]float64 literal is not a type