NSAttributedStringBuilder.swift

import Foundation

@_functionBuilder
public class NSAttributedStringBuilder {
    public static func buildBlock(_ components: NSAttributedString...) -> NSAttributedString {
        let att = NSMutableAttributedString(string: "")
        return components.reduce(into: att) { $0.append($1) }
    }
}

public extension NSAttributedString {
    class func composing(@NSAttributedStringBuilder _ parts: () -> NSAttributedString) -> NSAttributedString {
        parts()
    }
}