import SwiftUI

struct TextFormatting: ExpressibleByStringLiteral, ExpressibleByStringInterpolation {
    struct StringInterpolation: StringInterpolationProtocol {
        var output: Text = Text(verbatim: "")

        init(literalCapacity: Int, interpolationCount: Int) {
            // TODO
        }

        mutating func appendLiteral(_ literal: String) {
            output = output + Text(literal)
        }

        // append bold text
        mutating func appendInterpolation(bold: String) {
            output = output + Text(bold).bold()
        }
    }

    var text: Text

    init(stringLiteral value: String) {
        text = Text(verbatim: value)
    }

    init(stringInterpolation: StringInterpolation) {
        text = stringInterpolation.output
    }
}

extension Text {
    init(_ html: TextFormatting) {
        self = html.text
    }
}

let boldly = "boldly"

struct ContentView : View {
    var body: some View {
        List(0 ..< 5) { item in
            Text("To \(bold: boldly) go")
        }
    }
}