Defining Swift functions that operate on Types instead of values

Question

In Swift, the ? operator takes Types as parameters, instead of values:

var z = 42? // won't create an Optional<Int> and won't compile
var z : Int? = 42 // ? takes Int and give a Optional<Int>

How can I create my own functions, or operators that work on Type instead of values?

Answer 1

What you want to achieve is not possible.

However there is a workaround: you can create a custom operator that given a literal or variable, converts it to an optional. Swift doesn't allow using the ? character in custom operators, I am choosing a random combination, but feel free to use your own:

postfix operator >! {}

postfix func >! <T>(value: T) -> T? {
    return value as T?
}

Once done, you can use it as follows (output from playground):

10>! // {Some 10}

"Test">! // {Some "Test"}