Comment by schwurb

What you are doing is prototyping. Which is a good thing. However, writing stuff down is also another form of prototyping, which different tradeoffs.

With coding, you are confined to formal syntax and semantics, but if the code (even partially) works, you can be more confident in your design.

With paper, you can plan as high-level as you want, with the danger of being too highlevel and overlooking things.