>>5Yes, I definitely agree. A dynamic language as expressive as Lisp excels with that kind of evolution. Because the problem, which is like what you suggested, is that we don't understand the problem today and likely tomorrow. So, Lisp certainly has an advantge when understanding the problem space.
However, I'm of the opinion writing with an ever changing understanding is still detrimental in itself. I honestly struggle remembering all those kinds of implicit complexities that creep up. I'd rather try to understand the problem, draw the line somewhere, and then design from the ground up. Because in Haskell, creating constraints improves my focus of correctly solving the problem at hand.
I find that kind of style works better for me. Maybe it doesn't for you.
>>6*Data types with named records and fields.