Ceci n'est pas une pipe

    const query<std::string> titles_playing_nearby =
        .jump(movies, local_screens->current_movie_id == movies->id)


Here we take a query (local_screens) and call one of its methods (jump()), to produce another query; then call one of its methods to produce another query; and one of its methods to produce the query titles_playing_nearby.

It is tempting to read such code as a pipeline, i.e. an instruction to perform the following tasks, either sequentially or in parallel:

I find pipeline thinking very useful, and in fact the methods where(), jump() etc. have deliberately been made compositional, so that pipeline thinking works when you chain them together. Still I must sound a small note of caution: I have no idea whether such pipelines are real. I don't know whether all the postulated streams and processing stages actually exist. I know that quince produces SQL queries whose output is as if produced by a real pipeline, but queries are executed by the DBMS, and it can use any strategy it likes to get to that output.