Perl とかにある宇宙船演算子もいいかも。 @swift-4.2.4

infix operator <=> enum Comparison { case less case equal case greater } func <=> <T: Comparable>(lhs: T, rhs: T) -> Comparison { if lhs < rhs { return .less } else if lhs > rhs { return .greater } else { return .equal } } let a = 2 let b = 3 switch a <=> b { case .less: print("a < b") case .equal: print("a == b") case .greater: print("a > b") }

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