Writing Specifications

Specifications are used to retrieve information. They begin with a model. The model describes the types of facts, and how they are related to each other.

const model = buildModel(b => b
  .type(Site)
  .type(Post, m => m
    .predecessor("site", Site)
  )
);

The model is used to create a specification. Given a starting point, the specification finds all facts that match a set of conditions.

const postsInSite = model.given(Site).match((site, facts) =>
  facts.ofType(Post)
    .join(post => post.site, site)
);

Call the j.query method to retrieve the facts.

const posts = await j.query(postsInSite, site);