proposal: Computed data queries

Sometimes we want to query data using a dynamic query that isn't supported in hypergraph, and instead of returning an entity, we might want to return a computed value.

For example, there are a set of entities with the Episode type. Each episode points to a Podcast. I might want to calculate how many episodes a podcast has.

This would require a mechanism for users to specify queries to make against the graph with syntax for aggregations, selecting, filtering, etc. We could make it type safe by integrating it with our schema language.

実装ファイル、テスト、エントリポイントは指定されていません。まず既存のハイパーグラフクエリ API とスキーマ言語 API を調査し、次に集約、選択、フィルタリング、計算値の範囲と受け入れ基準を定義してください。