# Alloy Authors - Practical Alloy - Meta-capabilities (Highlights) ![rw-book-cover|256](https://readwise-assets.s3.amazonaws.com/static/images/article1.be68295a7e40.png) ## Highlights - all v : var$ | no v.value ([View Highlight](https://read.readwise.io/read/01jv2ag54akg3mskg5qeta30nb)) ^888705872 Initially all mutable elements are empty