The algorithm powering iHarmony

enum NaturalNote: String { case C, D, E, F, G, A, B } enum Accidental: String { case flatFlatFlat = "bbb" case flatFlat = "bb" case flat = "b" case natural = "" case sharp = "#" case sharpSharp = "##" case sharpSharpSharp = "###" func applyAccidental(_ accidental: Accidental) throws -> Accidental {...} } struct Note: Hashable, Equatable { let naturalNote: NaturalNote let accidental: Accidental ... static let Dff = Note(naturalNote: .D, accidental: .flatFlat) static let Df = Note(naturalNote: .D, accidental: .flat) static let D = Note(naturalNote: .D, accidental: .natural) static let Ds = Note(naturalNote: .D, accidental: .sharp) static let Dss = Note(naturalNote: .D, accidental: .sharpSharp) ...