Cool that you’re trying something new out! I also often find prefix arguments a bit unintuitive in my flow.

First of all, you’re right that you could do (eat nil 4) to simulate the prefix argument. I do this in a number of my helpers.

For my advice on your code, I think it would be easier to understand if you used a let* block to assign meaningful variable names. I’m writing this from my phone, so it’s hard to give a detailed example, but:

(let* ((eat-buffers (match-buffers "\*eat\*"))
       (last-buffer (last (sort eat-buffers))))
 ;; Body
)

And so on. This would let you reuse some values, and would also reduce the amount of nesting in your code.

Edit: Missed a few parentheses, fixing syntax highlighting