> One could write the same code in python/javascript with using lists and strings and recursion in a similar way, no?
That point is made in the article. You'd need to invent a language for writing the formulas as strings, and handle it with a scanner, parser (for which you pick an output tree format). Then do the differentiation on the tree format, and finally reformat the transformed code back to a string to be passed to the character-based "eval".
That point is made in the article. You'd need to invent a language for writing the formulas as strings, and handle it with a scanner, parser (for which you pick an output tree format). Then do the differentiation on the tree format, and finally reformat the transformed code back to a string to be passed to the character-based "eval".