RootStream

Root streams can perform an intial effect prior to emitting the resulting cursors and effective queries.

Stream effects are used for GraphQL subscriptions. Convenience methods are provided to cover the cases where only one of the query or the cursor are computed

If only the query is computed the default root cursor for the mapping will be used. If only the cursor is computed the client query (after elaboration) is used unmodified ... in this case results of the performed effect can only be passed to the result construction stage via the environment associated with the returned cursor.