Using map[string]int as parameter of type map[interface{}]interface{}

I have a function:

func ReturnTuples(map_ map[interface{}]interface{}) [][]interface{} {

In which I'm trying to call like this:

m := make(map[string]int)
m["k1"] = 7
m["k2"] = 13
fmt.Println(ReturnTuples(m))

But I'm getting

cannot use m (type map[string]int) as type map[interface {}]interface {} in argument to ReturnTuples

Shouldn't it work since string and int both implement interface{}?

I've searched and the best I could find was https://stackoverflow.com/questions/26975880/convert-mapinterface-interface-to-mapstringstring but it won't answer why I cannot use m as an argument.

I also believe that if the argument of the function were only interface{} it would work too, since map[something][something] implements interface, right? What is the best way to do it, and why it won't work in my case?

A solution to your problem, simply initiate the map as an empty interface of empty interfaces:

m := map[interface{}]interface{}

then you can assign any type key or value you want in the 'ReturnTuples' function.

playground example

NOTE: remember that if you want to use the values later as the original types, you will need to use type assertion because now they are of type interface{}

You may do something this like this, were anything is one map value which you can get using a for loop:

switch v := anything.(type) {
      case string:
            fmt.Println(v)
      case int32, int64:
            fmt.Println(v)
      case string:
            fmt.Println(v)
      case SomeCustomType:
            fmt.Println(v)
      default:
            fmt.Println("unknown")
}

If you are looking for an explanation for the "why"
@ymonad gave a full answer so I wont repeat it again.

hope it make sense

PS: don't get the down votes on the question, a legit one in my eyes...

You can type assert in the function itself.

func test(m interface{},key interface{}) bool {	// Map is passed as reference
        ma := m.(map[interface{}]interface{})
	    if _, ok := ma[key]; ok == false {
		....
}