[cle]

Indeed, and they are even worse than that, because Streams in Java can even be parallel streams and be processed by a thread pool. So it’s not enough to know that it’s a Stream, you have to know what kind of Stream, and if it’s a parallel Stream, what threadpool is it using? How big is it? What else uses it? What’s the CPU and memory overhead of the pool? What happens when a worker thread throws an exception? Etc. These are all hidden by the abstraction but are usually things we always care about as consumers of the abstraction.