What are result builders and how are they implemented?

Result builders enable creating DSL-like syntax by transforming sequences of statements.\n\n• **Basic Result Builder:**\n\n@resultBuilder\nstruct ArrayBuilder { \n func buildBlock(_ components: T...) -> [T] {\n return Array(components)\n }\n \n func buildOptional(_ component: [T]?) -> [T] {\n return component ?? []\n }\n \n func buildEither(first component: [T]) -> [T] {\n return component\n }\n \n func buildEither(second component: [T]) -> [T] {\n return component\n }\n}\n\n\n• **Usage:**\n\n@ArrayBuilder\nfunc makeArray() -> [String] {\n "First"\n "Second"\n if Bool.random() {\n "Random"\n }\n "Last"\n}\n\nlet array = makeArray() // ["First", "Second", "Random"?, "Last"]\n\n\n• **SwiftUI Example:**\n\n@resultBuilder\nstruct ViewBuilder { \n func buildBlock(_ content: Content) -> Content where Content: View {\n return content\n }\n \n func buildBlock(_ c0: C0, _ c1: C1) -> TupleView<(C0, C1)> where C0: View, C1: View {\n return TupleView((c0, c1))\n }\n}\n\nstruct ContentView: View {\n @ViewBuilder\n var body: some View {\n Text("Title")\n Button("Action") { }\n }\n}\n\n\n• **Advanced Features:**\n• buildArray for loops\n• buildLimitedAvailability for availability\n• buildFinalResult for post-processing