Solving the shortest grid path problem in Swift

Routes.swift

indirect enum Route : CustomStringConvertible {
    case End
    case Down(Route)
    case Left(Route)
    
    var description: String {
        switch self {
        case .End: return ""
        case .Down(let way): return "⬇︎\(way)"
        case .Left(let way): return "⬅︎\(way)"
        }
    }
    
    static func findRoutesFrom(x: Int, _ y: Int) -> [Route] {
        switch (x, y) {
        case _ where x < 0 || y < 0:
            return []
        case (0, 0):
            return [ .End ]
        default:
            return findRoutesFrom(x, y - 1).map() { .Down($0) } + findRoutesFrom(x - 1, y).map() { .Left($0) }
        }
    }
}

let routes = Route.findRoutesFrom(5, 3)
print("Found \(routes.count) routes")
for i in 0 ..< routes.count / 4 {
    print(routes[i * 4 ..< (i + 1) * 4])
}
if routes.count % 4 != 0 {
    print(routes.suffix(routes.count % 4))
}

This code belongs to http://www.obqo.de/blog/2015/11/04/how-many-ways-to-find-a-way/