Why does F # output int in this function?

Question

In F #, I can combine strings with an operator +like this:

let myString = "one" + "two"

But when I create a function that takes two arguments and applies the same operator, and I put it in the module declared before using it, F # writes the types as integers:

module StringFunctions = 

let add str1 str2 = 
    str1 + str2

The call below gives me a build error: "It is expected that the expressions will be of type" int ", but there is a type of" string "here:

let str3 = StringFunctions.add "three" "four"

Why does F # issue this as an int? I assume that this cannot be a general method, because not all types will implement the operator +, but why does it accept an int?

Answer 1

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