title: Swift - why can't lazy properties be readily made read only
body: <p>Can anyone please explain this comment re lazy properties by neuburg in iOS 9 swift fundamentals book ... </p>
  
  <p>"There are some minor holes in the language: lazy instance properties can’t have setter observers, and there’s no  lazy let  (so you can’t readily make a lazy instance property read-only)" .... Particularly about no lazy let preventing ability for read only</p>