The theory is the result of listening to the problem. When the theory acquires a life of its own because some people like it more than the real world, all kinds of uninspiring, uninteresting things happen, so the key is both to listen to the problem and to study the theory. But always remember that just as much theory is bunk as there are buggy solutions. There is nothing more wrong with "theory" than "solutions" – both their quality and their applicability are orthogonal to their existence.
Re: "Choose the Right Language" in "Tutorial" by Norvig and Pitman (Usenet article).
https://groups.google.com/forum/#!msg/comp.lang.li...[groups.google.com]