Meta

Overview

Libs and specs can define arbitrary meta or metadata. Many of xeto's built-in features leverage meta to annotate specs. For example, the sealed meta is used by the compiler to indicate that a spec cannot be subtyped. Both lib and spec meta is a normal dict, but uses special rules for static typing. Spec meta tags are defined as slots on the sys::Spec type and lib meta tags on sys::Lib. You can use mixins to add new spec/lib meta tags. Note all Spec/Lib meta tags must be defined as nullable (since they always optional).

Syntax

New meta tags are defined as mixin slots:

+Spec {
  // new spec meta tag
  specMetaTag: Type?
}

+Lib {
  // new lib meta tag
  libMetaTag: Type?
}