Nil coalescing for optionals in debug prints

To make it easier to use Optionals with string interpolation in debug prints in Swift, we can define our own operator that lets us use a String as default value independent of the Optional type.

infix operator ???: NilCoalescingPrecedence

func ???<T>(
    optionalValue: T?,
    defaultValue: @autoclosure () -> String
) -> String {
    optionalValue
        .map { String(describing: $0) } ?? defaultValue()
}

var url: URL?

// assign a URL some time later
url = URL(string: "https://example.com")

print("The URL is \(url ??? "nil")")

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