Sequence with KeyPath

KeyPath.swift

extension Sequence {
    func map<T>(_ keyPath: KeyPath<Element, T>) -> [T] {
        return map { $0[keyPath: keyPath] }
    }
}

extension Sequence {
    func sorted<T: Comparable>(by keyPath: KeyPath<Element, T>) -> [Element] {
        return sorted { a, b in
            return a[keyPath: keyPath] < b[keyPath: keyPath]
        }
    }
}