I've programmed professionally in a visual flow language which supported loops, and you're dead-on about nested loops being the hardest part. My understanding i

I've programmed professionally in a visual flow language which supported loops, and you're dead-on about nested loops being the hardest part. My understanding is that the problem is caused by it being hard to think about the actual values on which each component is working. I have this idea that this problem could be solved with a visual flow language where, at runtime, you could see the collection of all values that each node is emitting during program execution, rather than just the current value. I have not seen that approach in any flow language, so maybe I'll implement this idea in the future as an experiment.