We call the "lines" in Rockpool, "Rules" or "Flows" - I like the name "Flows" better since it's a lot less jarring. Line is fine, too, I know what you're talking about.
At the moment the only way to branch a flow is to output it into a variable, and then use that variable as an input on subsequent lines. There are a couple of reasons why we went this route:
- It gets visually confusing really quickly
- It's not necessary in many cases since you can just re-use the same input
If you want to try the absolutely bleeding-edge software you can find it here: https://github.com/pimoroni/flotilla-pre
Rockpool on the Raspberry Pi 2 will always be slower than running it on a desktop, but we're eager to make it at least usable. Epiphany browser isn't the most forgiving of targets, either.