Why can't Swift's greater-than or less-than operators compare optionals when the equality operators can?

Question

In Swift 3, this is a compile error, if I use > or <

let a: Int?
guard a > 0 else {return}
guard a < 0 else {return}
         


        

Answer 1

Optional equality works logically, comparison doesn't.

• 5 == 5 = true
• 5 == nil = false
• 5 == 6 = false
• nil == nil = true

Those all make sense, but these don't:

• 6 > 5 = true
• 5 > 5 = false
• 5 > nil = ??
• nil > 5 = ??

This type of comparison does not have a simple answer, nor will that answer be the same depending on the use case.