Several of my projects go through this time-consuming and tedious phase:

1. design a LED pattern for a geometry of WS2812 LEDs
2. implement it with e.g. FastLED
3. write to Arduino and see results
4. goto step 1

The second step, implementing different ideas in C with FastLED (or similar) takes a lot longer than I'd like it to. How is this step usually solved? Are there higher-level software solutions? Specialised idea-testing hardware?

I'd like to easily try out ideas such as "what if these four LEDs blinked magenta every second, while a gradient was cycling around the gradient over here".