The listing functions shared by repository adapters (DDD.Repository.Ecto) and projections (DDD.Projection): list/1, page/1, slice/1 and count/1.

Options (all optional):

• :filter - a DDD.Filter expression
• :spec - a DDD.Specification (one that defines to_filter/1); combined with :filter
• :order - :title, {:desc, :title} or [desc: :created_at, asc: :title]. The primary key is always added as the last tie-breaker, so the order is total and pages are stable. Default: the primary key.
• list/1: :limit (default: all)
• page/1: :page (default 1), :page_size (default 20, at most 1000)
• slice/1: :limit (default 20, at most 1000), :after (a DDD.Slice's next_cursor)

Everything returns {:ok, result} or {:error, %DDD.Error{kind: :business}} with the code :invalid_filter, :invalid_order, :invalid_page or :invalid_cursor: these options often come straight from a client's request, so a bad one is an answer, not a crash.