func makeFunc<A, R>(argType: A.Type, returnType: R.Type, body: @escaping (A) -> R) -> (A) -> R { return body } makeFunc(argType: Int.self, returnType: String.self) { String($0) }(3) makeFunc(argType: (Int, Int).self, returnType: (String, String).self) { (String($0.0), String($0.1)) }((1, 2)) makeFunc(argType: Void.self, returnType: Void.self) { _ -> Void in print(33) }(()) // error makeFunc(argType: ().self, returnType: Void.self) { _ -> Void in print(33) }(()) // error makeFunc(argType: Void.self, returnType: ().self) { _ -> Void in print(33) }(()) print( ().self is Void.Type ) // false print( Void.self is ().Type ) // true