Syntactic decorators

[justinmchase]

• The pattern language needs to support decorators, (e.g. @keyword, `@desription "A pattern that matches entitites")
• The decorator is appended to the metadata of objects returned by the rule its attached to using the javascript Reflect api
• Object metadata needs to be retained any time a return value is cloned for any reason

example

@description "Defines an entity type"
EntityKeyword = "entity";

@description "Defines an entity field"
FieldKeyword = "field";

@keyword
Keywords = EntityKeyword | FieldKeyword;
---
input: "entity"
metadata:
- name: description
  value: Defines an entity type
- name: keyword