Since direct integration of data flow and control flow is neither reasonable nor desirable, a heuristic is needed to productively combine the two. […] Compared to an approach that integrates control flow and data flow, such as PL/SQL, embedding in an existing scripting language is a much lower development and maintenance effort. It will also be much easier for users, who will be able to use existing development tools (IDEs, debuggers, etc.) to work with their scripts.
via NoSQL databases