Paul Graham on seperating coding and planning

24 Jun 2007 7:56 - (0) comments

Paul Graham in On Lisp:

Experienced programmers know that no matter how carefully you plan a program, when you write it the plans will turn out to be imperfect in some way. Sometimes the plans will be hopelessly wrong. Yet few of the victims of the plan-and-implement method question its basic soundness. Instead they blame human failings: if only the plans had been made with more foresight, all this trouble could have been avoided. Since even the very best programmers run into problems when they turn to implementation, perhaps it’s too much to hope that people will ever have that much foresight.

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As Montaigne found, nothing clarifies your ideas like trying to write them down. Once you’re freed from the worry that you’ll paint yourself into a corner, you can take full advantage of this possibility. The ability to plan programs as you write them has two momentous consequences: programs take less time to write, because when you plan and write at the same time, you have a real program to focus your attention; and they turn out better, because the final design is always a product of evolution. So long as you maintain a certain discipline while searching for your program’s destiny—so long as you always rewrite mistaken parts as soon as it becomes clear that they’re mistaken—the final product will be a program more elegant than if you had spent weeks planning it beforehand.