It’s unrealistic to expect that the specifications for a program will be perfect. You’re better off if you admit this up front, and write programs in a way that allows specifications to change on the fly. (The structure of large companies makes this hard for them to do, so here is another place where startups have an advantage.) Everyone by now presumably knows about the danger of premature optimization. I think we should be just as worried about premature design — deciding too early what a program should do.
