I have again an idea… I know, ideas are cheap, but still:
“As is” I find it difficult to add any “own” function to ulisp’s source simply because I don’t feel very secure with C; you explained very well how this is done, but the issue remains — and perhaps exists for others, too.
Now, my question: would it be possible to create some tool that takes a file (of Lisp definitions) and generates out of it C-source? — That would make creating extensions rather easy.
(My underlying issue: we are starved of RAM, even in the most powerful boards, and save-image is even worse unless you use SD-card-support. I want to make a sort of chatbot, and chatbots need, essentially, a lot of text. If the text is immutable, it might be defined best within a ulisp source extension.)